Democratic presidential candidates Hillary Clinton and Sen. Bernie Sanders laid out some of their key differences Monday in a Fox News Channel town hall event in Michigan -- including Clinton springing a surprise alternative to Sanders' millennial-friendly, free-college-tuition plan.

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Sanders opened by defending his auto-bailout vote, which Clinton hit him on during their debate the night before.

“What I did not vote for was the bailout of Wall Street. … She did vote for that,” Sanders said, referring to Clinton’s time as a New York senator.

The front-running Clinton and the Vermont senator made their cases in Detroit on the eve of Michigan’s Democratic and Republican presidential primaries.

Most polls show Clinton with a double-digit lead in Michigan, as she enters the primary with 1,130 delegates, compared to 499 for Sanders. Either needs 2,383 delegates to win the party nomination. The two will also compete in the Mississippi Democratic primary Tuesday.

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Sanders on Monday night also hammered his message of economic equality and prosperity.

“There is no candidate in this race who has talked more about poverty than I have,” he said. “In the richest country in the history of the world, we have more income and wealth inequality than any other major country. We have too many people living in poverty. We have got to change our national priorities.”

He also repeated his calls for helping roughly 29 million Americans without health care, arguing the problem is in part the result of pharmaceutical companies gouging the country.

“We have many more (Americans) who are underinsured,” Sanders said. “And we are getting ripped off big time by the pharmaceutical industry, which are charging us the highest prices in the world.”

Clinton, meanwhile, was asked at the outset of the event about the ongoing classified email investigation being conducted by the FBI, claiming once again that she was not notified that she is a subject of that investigation.

“Absolutely true,” Clinton responded to the question by Fox News’ “Special Report” host Bret Baier.

Clinton also said neither she nor her lawyers have been informed that any members of her staff or former staff are targets of the investigation, which focuses on her use of a private email server while secretary of state.  

Clinton also stood by decision, as part of the Obama administration, to remove Libyan dictator Muammar Qaddafi in 2011. But she acknowledged the “deeply regrettable” aftermath, in which the Islamic State terror group has flourished in parts of that country.

“If there had not been that intervention … we would be looking at something much more resembling Syria now,” Clinton said.

She also argued that the United States and its allies saw more turmoil in “leaving a dictator in place,” like Russia has done with Syrian leader Bashar al Assad. And she said the Libyan people have since had two fair elections to "get themselves a better future."

Clinton also used the forum to introduce her answer to Sanders’ popular free-tuition college proposal, unveiling the outlines of a plan in which students will no longer have to borrow money to attend a public college or university.

She said the New College Compact plan would also help with non-tuition costs.

“It is absolutely imperative that we make college affordable,” Clinton said.

Both candidates also explained their position on abortion, amid continuing debate about stopping the procedure after five months of pregnancy, with the exceptions for the life and health of the mother and baby.

“I am very strongly pro-choice,” Sanders said. “That is a decision to be made by the woman, her physician and her family.”

Clinton said she objects to the recent effort in Congress to pass a law saying no such exceptions after 20 weeks of pregnancy.

“Because although these (exceptions) are rare, they sometimes arise in the most complex, difficult medical situation,” she said.