Certainly there is a lot of voter intimidation, control of the press, etc. behind it, but I think that's precisely what is being debated here.
Nazi's were not the majority party when Hitler ran for president, they were the largest party, but not majority. They weren't even a majority even when Hitler was appointed (not voted) chancellor by Paul von Hindenburg, the man who won the presidential election. There were a few more steps before he acquired absolute power, but none of them involved voting. It's interesting, read the article.
Like I said, it's a common misconception.
(You could not "vote" a chancellor. In a lot of perfectly valid democracies, the PM position is always appointed, never directly voted, usually from the larger party or the at least the candidate most likely to pass a (constructive) motion of no confidence. So he was elected legally per the correct democratic process. Cleanly/Fairly -- that's another question. But would you really be surprised Hitler could win elections? He had pretty ridiculously good reputation in some circles. He would have likely polled pretty well even in the US.).