"And this is where I put on my state treasurer's hat again for just a moment to give the most important lesson: The people of Germany in a free election selected the Nazi Party because they made great promises, that appealed to them because they were desperate and destitute," Mourdock said.
He said the Nazis targeted one group after another, "but ultimately they went after the Jews, they deprived them of their property, their rights, their citizenship. Because they were bankrupt."
Mourdock said the circumstances that carried the Nazis to power were economic and that they raised his concerns about America's current situation dealing with debt.
"The truth is 70 years later we are drifting toward the tides of another beachhead with the bankruptcy of America," he said.
Mourdock explained afterward it wasn't meant as a direct comparison to President Barack Obama and the Democratic Party.
In a tweet Saturday afternoon, Indiana Democratic Party Chairman John Zody asked the state's Republican Party leaders to denounce Mourdock's comparison.
Mourdock has faced criticism for remarks before. During a debate in the final weeks of his U.S. Senate bid in 2012, the tea party-backed Mourdock said a pregnancy resulting from rape is "something God intended."
Mourdock lost that race to Democrat Joe Donnelly and state Republican leaders have kept their distance from him since then. National Republicans used his stumble as an example when training candidates on how to avoid gaffes on the campaign trail.