Was there a constitutional mechanism to overturn the election of Adolf Hitler?

To answer your question: of course there were "legal" mechanisms to do anything. The President could have dismissed Hitler at any time. The Reichstag could have passed laws to do anything they wanted, including having BOTH Hindenberg and Hitler removed. The "legal" means are always there. The important thing however is the will of the people.

To answer your question specifically... Under the Weimar Constitution:

1. The President could dismiss the Chancellor (Hitler) at any time.

2. The Reichstag could force the resignation of the Chancellor (Hitler) or any other government minister at any time by a vote of no confidence.

3. When Hitler became President and took power by emergency decree, the Reichstag could have legally nullified this decree by vote if it so chose.

So, it was legally within the power of the Reichstag to block or remove Hitler even after he was elected. Even after he was president, the Reichstag could have not only blocked his emergency decree, they could have voted him down in no confidence and forced him to withstand a plebiscite, and even if he passed this plebiscite, the Reichstag had power over both the purse of the Reich and had the power to remove ANY minister, so legally speaking they could have rendered even President Hitler powerless, if they so chose.

The dynamics of the situation were that Hitler actually had a minority of support, but those who did support him were near-fanatical; that is why he was able to take over. At the time many people, typically upper middle class wage earners were dismayed at the rise of the National Socialists, but they were drowned out by the parades, celebrations and esprit of that party.

If you remember what it was like when Obama was elected, how there were large cheering crowds, and Oprah crying, and the news casters enthusiastically declaring a new age. Imagine that and multiply it times 100 and you will have some idea what it was like. In every town Nazis were parading up and down through the streets carry banners. They were firing old corrupt bureaucrats and replacing them with new "modern", "efficient" officials. They were re-arranging water works, charity systems, road building, you name it. The old conservatives that opposed this were in the majority, but they basically just stood by with their mouths open while this hurricane passed by them.

There is a book called "The Nazi Seizure of Power" by William Allen which describes what happened through the lens of single town. If you want to understand the political forces involved I suggest starting with that book.

@Tyler Durden is substantially correct i.e. the Wermier President (then the Great WW1 General Hindenburg) did have the constitutional authority to dismiss Hitler as Chancellor of Germany, at anytime of his choosing.

What is missing from Druden's answer and all the other's to date is the acknowledgement that German democracy was doomed, one way or the other.

There has been an eerie airbrushing out of history of the central, controlling role that communist operating under the direct command of Communist Party in the USSR, played in the rise of Fascism in both Italy and Germany. In short, had there been no Communist, there would have been no Fascist.

If you go back and look at the primary sources from the day, its readily apparent whom the Fascist where paired up against in the street fights. It began in Italy where Red Socialist violence, terrorism, sabotage and strikes grew so disruptive that people where actually beginning to starve in major cities. Mussolini didn't make it into power and a Cole Porter song because he made the trains run on time, he hit the big time because he got the food trains running period by busting Red Socialist heads.

If the Communist had never pushed Italy to the brink, Mussolini would have remained another failed Marxist editorialist.

The same happened in Germany. Whenever you read about the brown shirt battling their "opponents" in street fights or in terrorizing the "opposition" those are code words for Communist and their knowing and unknowing fellow travelers. The number of battles, attacks and defense fights against non-Communist is trivial.

A little common sense is all it takes to know that something is missing from the historical narratives that air bush out the role of the Communist. The Germans are an order loving culture to put it mildly and in the 1930s they were class riven to a degree not seen in America since 1820s at the latests (with the exception of perhaps the deep south or early 1800s Hudson River valley.) They would have never voted for nor made a coalition with a mass of violent, lower-class street brawlers unless they saw them as the lesser of two evils.

One need only remember how easy Hitler found it to blame the Communist for the Reichstag fire before he had dictatorial powers or control of the media. The German people found it perfectly creditable that Communist had burned down the Reichstag because the Communist had been setting fires, sabotaging infrastructure, provoking strikes, causing riots, beating people in the streets and generally raising hell for the nearly 15 years by that point.

Communist violence allowed the Brownshirts to create a narrative of themselves as heroic protectors of German lives, property, social order and culture. Worse, the narrative was close enough true for politics.

The vast majority of Germans believed (correctly as the end of the Cold War would prove eventually) that the German Communist were operating under the control of the the Soviet Union, which by 1932 meant operating up the control of Stalin. Most Germans understood that German Communist sought to destabilize the German economy, political system and social structure to trigger the crises of capitalism that Communist ideology said would inevitable occur and lead to the Communist utopia. They also knew that one of the waypoints on the road to the utopia was the eradication of all non-Communist cultures and beliefs. (See Mao's Cultural Revolution as the most extreme manifestation.) Stalin's destruction of the churches, which began in 1930-31, made it creditable that German culture would not survive Communist rule. (Nobody knew then that Communist all become vitriolic nationalist within a generation.)

In additon to understanding the threat poised by communism, when evaluating Germany's election of Hitler we have to remember that we have the advantage of hindsight on many issue. We have to try and see how Hitler looked back then when he and the Nazis where a new idea.

Sadly, Hitler's public ideology wasn't actually extreme for the day. Space precludes but suffice it to say that

1. democracy did not have a strong foothold in Germany yet.
2. Hitler's racial theories of a master race were just a slightly dialed up version of the then accepted mainstream science of white racial superiority
3. Eugenic likewise was widely popular with the educated, urban secular demographic, and completely uncontroversial. Only the deeply religious opposed it.
4. Free-market capitalism was seen world wide by all but entrepreneurial classes as a dead letter. (See the unconstitutional extremes of the National Recovery Administrations in the US as a demonstration of the extreme economic ideas of the day.) , Hitler's call for socialist state control of the economy with a guarantee of jobs and economic security for all with none to rich and none to poor, likewise, did not seem extreme.
5. Hitler swore up and down that as veteran of the trenches of WWI, he would never start a another war in Europe. A lot of people who didn't like Hitler, such as Rommel, believed him on that point.
6. Lastly, Every German, even the Communist supposedly, wanted to rearm and have Germany return to the status of full nation with control over its own military and destiny. (the Weimar Germany government had been systematically violating the arms restrictions in the Treaty of Versailles, going so far to secretly ally with the Soviet Union in 1923 for weapons and doctrine development. That alliance lasted until Hitler came to power. Blitzkrieg was tested out on the plains of the Ukraine in the 1920s.) Hitler's overt militarism, then, did not place him outside the mainstream.

During the Cold War, numerous factors, predominately I suspect terrified denial, caused us to whitewash Communism, especially Stalinism, and tell ourselves it wasn't that bad. We've all been saturated in horrors of Fascism since birth but Communism was kept off stage and actively down played. In that distorted lenses, the actions of Germans, Italians, Spanish etc to escape Communism seem excessive and unnecessary.

But after all we learned after we got a peak behind the iron curtain after Communism fell, that is no longer a credible model. Stalin intentionally killed at least 4 million Ukrainians in the holomador to pay for the factories that built his offensive armies. He clearly believed in the marxist doctrine of historical inevitability and the violent triumph of Communism and planned to see it through. In 1936, before the Great Terror, the Soviet Union had the largest, most technologically and doctrinally advanced military in the world. Had Germany fallen to Communism in the early 1930s or just been so disrupted as to not to be able to oppose Stalin, Stalin instead of turing in paranoia inward, instead have turned outward and swept through Europe just as Hitler did and just as bloodily.

In 1932, juxtaposed against the concrete reality ceaseless disruptions and attacks of Communist and the very real and obvious existential threat poised by Stalin, letting the Nazis into power seemed like an acceptable risk. A lot of anti-nazi, anti-communist germans seemed to think of it as fighting fire with fire. (They forgot how tricky backfires are in real fire fighting, I suppose.)

So, in the end, even though as a hereditary aristocrat Hindenburg throughly hated the socially inferior Hitler and his (racially) egalitarian Socialist ideology, and he had the constitutional power to keep Hitler out of power , Hindenburg along with all other anti-Nazi and anti-communist Germans believed they were backed to the wall and forced to tolerate and ally with Hitler. It was the threat of the Communist, not the lack of a lack of a constitutional mechanism, that brought Hitler to power and kept him there long enough to establish his dictatorship.

It was only around 1936, after several years of over the top Keynesian economic policy providing full employment followed by coup of reclaiming the Rhineland, did Hitler become venerated by the majority of the population. Even then substantial opposition existed in the military and big business but no one could do anything without risking letting the Communist in. Even during the war, it was largely the fear of Communism that kept major segments of the German population fighting long after they knew the war lost otherwise.

Communism was the central axis around which all international events revolved from 1917-1992. You can't understand anything about the rise of Fascism, or any other major international events of the era, without understanding the role Communism played.

Nobody mentioned that Hitler also withstood several internal party votings to the position of the party leader. It is difficult to say whether these votings were fair and what would happen if he failed to secure the majority, but at least we know that Mussolini was deposed by the internal party means.

The election of March 5th 1933 was not a free and fair election anymore, unlike today's elections in the US and Europe. Opposition party members had gotten arrested and people intimidated, so the Reichstag opposition members, not all were present, were under intense pressure to do nothing about it.

There was a mechanism called voting against Hitler. Unfortunately, Hitler's opponents failed to set aside their differences and unite against him.

It is important to realise that Hitler did not gain dictatorial powers solely by virtue of winning a democratic election (though the Nazi electoral performance helped immensely). In fact, in the last generally free election of Weimar Germany, the Nazi party's share of votes had actually declined by over 4% compared to the previous one.

What really gave Hitler dictatorial powers was the Reichstag, including the opposition parties. Remember the Nazi Party failed to win a majority of seats there, even after the rather undemocratic March 1933 election. However, Hitler convinced the legislature to pass the Enabling Act by 444 to 84. Thus the Reichstag depowered itself, and effectively instituted a legal dictatorship in Germany.

This is the mechanism - voting against Hitler's Make-Me-A-Dictator-Act. The opposition delegates didn't have to support that law. In fact, 84 of them did not. Had the rest exercised their right to vote against Hitler's proposed law, the Nazis would not have gained dictatorial powers in this pseudo-Democratic fashion.

Once Hitler was made dictator of Germany, there was no realistic option to democratically oust the Nazis from power. Technically, the Enabling Act had a built in expiry date (1937), but this was a fantasy because the Nazis could (and did) ban all opposition parties. Thus when the time came the fully Nazi Reichstag simply rubberstamped a renewal. Similarly, Hitler's violation of the Enabling Act's already generous terms could technically be challenged in court, but in reality there's no prospect of success when the Nazis controlled law enforcement.

Having said all that, Hitler's rise to power was substantially backed up by Nazi paramilitary muscles. Throughout the process he and the Nazi party made liberal use of intimidation tactics. Even if he was stopped from "democratically" becoming a dictator, there's no saying that he wouldn't have taken over by force instead.