He kind of didn't. He fought a hard political battle spreading his hate rhetoric and unfeasible plans across Germany. He lost the 1932 election. Twice. Lost is a general term cause back then your party runs and if you're the leader of your party and your party has above the required amount of parliament seats, then you become the president. It wasn't until after the 2nd loss, where Hitler formed a shadow government and then essentially subverted the status quo government by making a deal with the current ruling party. That party was severely weakened by 2 failed elections, while at the same time Hitler's party was gaining traction with all the bad things happening in Germany and him promising to to fix it while spreading hate. They were the last party before Hitler's to hold power because they were the last ones to hold a majority. That was in 1933. Then Hitler's party was in rule until 1945.