Its not fair to view the German public of the time as a general voting block. I think the most the Nazis ever won was something like 35 - 40% of the vote in the '32 election. The major opponent was the communist party and at the time there was a lot of violence in the streets. It was common after party parades or gatherings for there to be a few dozen supporters dead after clashes between the nazi and communist supporters. So many Germans were more nervous about the potential violence should the Communists take power, after viewing the results from Russia which drove them into the arms of the Nazis.

After he took power, those people saw wages rise, unemployment fall, international recognition with the 36 Olympics etc. This was funded via borrowing and deficit spending so the general public was pretty supportive as they were reaping the benefits of this unsustainable growth of the economy. Initially the war was popular because of the speedy and relatively bloodless victories over Poland, France and Czechoslovakia.

To answer your question, yes there was a sizeable population nervous of him and his policies but the political party that represented them was outlawed, the leaders imprisoned or killed and the results were swept under the rug of fake prosperity.

Take a look at the electoral breakdown of the Weimar Republic's last elections, linked below.

The Nazis and other hard right groups had the strongest claim to popular legitimacy of any major political groupings in the last days of the Republic. The other two blocs-- the hard left Communist Party, and the democratic center parties-- were worse organized and individually smaller than the hard right.

When push came to shove, the democratic center parties and the Communists were unwilling to ally together to prevent the hard right from coming to power. (The center parties had spent most of the Weimar Republic keeping the Communists as far from the levers of power as possible.) And since they couldn't hang together, they most certainly hung separately.

https://www.reddit.com/r/AskHistorians/comments/3kn61g/z/cuyxrca?context=1000

As others in the thread have pointed out, the National Socialists never won 50% of the vote, and anyway, the 'German public' was a large group and are difficult to determine what their sentiment was.

Resistance to the National Socialists existed all along, but at certain stages, it grew. And as much as we, with the benefit of hindsight, would like to believe resistance grew because of the regime's appalling treatment of some of its victims (Jews, Poles, Russians etc), the main driver for resistance appears to be the idea that Hitler and the National Socialists were bad for Germany. Hitler's gamble over Czechoslovakia in 1938 emboldened some Army officers to contemplate a coup. The loss at Stalingrad did the same. But in these cases, the motivation was to overthrow Hitler because his continued rule was bad for Germany, not because he was a bad person.

Attempts to assassinate Hitler by civilians did occur, but were rarer, mainly because civilians lacked the resources, access or organisational structure to carry out a complex operation required to oppose a totalitarian government. And also because the National Socialists had done a good job, almost from the beginning of their reign in 1933, to divide and conquer their enemies. It's not accidental that the Niemoller poem has become so well-known for describing how groups were isolated and persecuted.

At the time of Hitler's rise to the Chancellorship, in January 1933, the organisations with the most potential to unseat him - the Army and the Communists - were quickly tamed. (It's no accident that when the Nazis first got seats in cabinet, the Interior Ministry - responsible for the police - was one of the first departments they took charge of) The Communists were framed, thanks to the Reichstag fire, as anti-German traitors and began to be locked up. At the same time, the labour unions had their assets seized, and the Nazis pushed through the Enabling Acts. Meanwhile, the Army was bought onside by the neutering of the SA in the Night of the Long Knives.

So was there a time when the general public might have realised where they were headed and tried to stop him? Not really. While Hitler's regime was delivering successes, hardly anyone wanted it to stop. And when the failures started to come, and serious failures only really began to accumulate when Germany was deeply embroiled in war in Russia, all the possible focal points where opposition may have gathered - the military, the other political groups, the persecuted minorities, labour unions, even churches - had been so neutralised by the regime they couldn't raise sufficient resistance to stop the downward spiral.

In addition to what has already been said, it's important to realize that there is no sudden on/off switch for the"general public" to realize that the Nazis were bad. Political consciousness is a slow, messy, and uneven process that differed depending on the demographics. The Communists for instance would have very quickly realized the Nazis had a murderous agenda for them - since they were quickly targeted and repressed. By contrasts revanchists who were still sore about the Firt World War were probably among the 30% or so of Germans who still supported the Nazis and believed they could win the war in 1944.

I don't think Hitler actually went off the rails like an unpredictable madman. He pursued a fairly clear agenda for two decades. The German public generally knew what he was up to and supported him. (He had 40% of the vote plus The Enablement Act is where the non-communist parties further backed him.) He was elected Chancellor in 1933. By that time, his book Mein Kampf had sold about a quarter million copies. Add that to his speeches prior to 1933 and it should be clear his goal was to take land in the East and that Jews were the main enemy. I've really grown to believe that the democracy of the people understood things and was much to blame.