It would be fair to say that Franz von Papen was a significant factor in Hitler being named Chancellor in 1933. I don't know how much you know about Hitler's rise to power so I'll start by giving an overview of events.

The scene begins on the 31st of July 1932. The Nazi party has just won 37.27% of the vote in the General election which was called by Franz von Papen in an attempt to shore up support for his chancellorship after he replaced Heinrich Bruning a few months previously. Whilst the Nazis had been disappointed by Hitler's loss to Hindenburg in the presidential election earlier that year by almost six million votes, their performance in the general election was the second highest percentage in the history of the Weimar Republic, surpassed only by the SPD in the first election following the overthrow of Kaiser Wilhelm II. The problem now remained for the Nazis of how to turn their electoral success into real power. Simply being the largest party did not give them the automatic right to form the Government, and they would need the blessing of Hindenburg to do so. In meetings between von Papen, Hindenburg and Hitler, Hitler made it clear that he would accept nothing less than the post of Chancellor. Naturally this was unacceptable to the others, who were not opposed to having Nazis in Government per se, but wanted to limit their influence and power as much as possible. According to Hindenburg's Chief of Staff Otto Meissner,

'The Reich President in reply said firmly that he must answer this demand with a clear, unyielding "No". He could not justify before God, before his conscience, or before the Fatherland the transfer of the whole authority of government to a single party, especially to a party that was biased against people who had different views from their own.'

This then lead to a bit of a crisis for the Nazi party. They had committed to following a policy of seizing power by legal means but this had led them into a dead end. They had reached their peak of electoral success but were still locked out of the halls of power. Fortunately for them, the Reichstag passed a massive vote of no confidence in von Papen's government and another General election was called. This election was fraught with violence, and the Nazi's low morale, low funds and the general apathy of the population towards repeated elections led to a fall in vote share for the Nazi party to 33.1%. Hitler still refused to join the Government except as Chancellor, and von Papen still hadn't solved the problem of lack of parliamentary support for his Government.

From this point in time, it is very difficult to see how Hitler could get into Government, let alone accept von Papen as his Vice-Chancellor. However, it is time to introduce a new character, that of Kurt von Schleicher, the Defence Minister and a close personal friend of Hindenburg. Schleicher wasn't a politician who was particularly fond of the spotlight, although he was very influential and knew his way around the back rooms of Berlin. Indeed, the word Schleicher translates into English as skulker. von Schleicher saw the unsustainability of von Papen's government and approached Hindenburg to make him Chancellor in his stead. Hindenburg agreed and von Schleicher became Chancellor. However, von Schleicher's chancellorship was not a very successful one. His plans for a public works programme to help combat the depression were undermined by the SPD and alienated many influential businessmen. His political plans to split the Nazi Party by offering Gregor Strasser, the leader of the left wing faction of the party, a senior Government position failed and Strasser was forced to leave the party. On the 4th of January 1933, von Papen and Hitler met and agreed support for a coalition government with Hitler as Chancellor and von Papen as Vice-Chancellor. von Papen met with Hindenburg and convinced him to agree, and on the 30th of January 1933 Hitler was appointed Chancellor of Germany. For most of the men in this story, there is not a happy ending. Heinrich Bruning fled the country in fear for his life, Hindenburg would be dead within two years. Both von Schleicher and Strasser were murdered in the Night of the Long Knives. Only von Papen, Otto Meissner and Heinrich Bruning would survive the war.

As we can see, Franz von Papen played a major role in bringing Hitler to power, and it would be fair to say that without him, the Nazi ascent to power would not have been as smooth. Whilst it was the Nazi's electoral success that got them to the point where they were considered a serious prospect for Government, it was von Papen who got them the final steps. Hitler was a relative political outsider who did not have the influence with the traditional conservative elites that von Papen did.