Former Maryland Gov. Martin O'Malley, currently a distant third in the race for the Democratic presidential nomination, used his final words in the CBS News debate on Saturday night to take one last dig at front runner Hillary Clinton:

"If you believe that our country's problems and the threats that we face in this world can only be met with new thinking, new and fresh approaches, then I ask you to join my campaign," he said in the second Democratic debate at Drake University in Des Moines, Iowa. "We will not solve our nation's problems by resorting to the divisive ideologies of our past or by returning to polarizing figures from our past."

While Clinton has been a polarizing figure nationally over the years, she has so far seen most of the Democratic Party happily coalesce around her ahead of the 2016 elections. In the second of six Democratic debates, her two remaining primary opponents sought to take her down a notch.

Clinton did a commendable job defending her record and her proposals for the future, but both O'Malley and Sen. Bernie Sanders of Vermont effectively challenged her on issues ranging from the federal minimum wage to the fight against ISIS. The two men in the race may win more attention from voters following the CBS debate, though perhaps not enough to block Clinton's path to the nomination.

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Sanders, assisted by O'Malley, launched the most forceful attack of the evening when he laid into Clinton's ties to Wall Street. After Clinton described her "very aggressive plan" to rein in big banks as well as the "shadow" banking industry, Sanders dismissed it with a simple, "Not good enough."

"Let's not be naive about it," he continued. "Why over her political career has Wall Street [been] a major-- the major-- campaign contributor to Hillary Clinton? You know, maybe they're dumb, and they don't know what they're gonna get. But I don't think so."

Sanders reiterated his call for breaking up the big banks and pointed out he is the only Democratic candidate without the support of super PACs. "I am running a campaign differently than any other candidate," he said. "We are relying on small campaign donors -- 750,000 of them and 30 bucks a piece. That's who I'm indebted to."

Clinton explained her support from Wall Street by pointing out that she was a senator for the state of New York when the September 11, 2001 attacks occurred.

"Where were we attacked? We were attacked in downtown Manhattan where Wall Street is," she said. "I did spend a whole lot of time and effort helping them rebuild. That was good for New York. It was good for the economy."

Clinton's response raised some eyebrows, and she was asked to respond to a debate viewer who reacted with skepticism on Twitter:

Have never seen a candidate invoke 9/11 to justify millions of Wall Street donations. Until now. @HillaryClinton #DemDebate — Andy Grewal (@AndyGrewal) November 15, 2015

"Well, I'm sorry that whoever Tweeted that had that impression because I worked closely with New Yorkers after 9/11 for my entire first term to rebuild," she said. "And so yes, I did know people. I had a lot of folks give me donations from all kinds of backgrounds, say, 'I don't agree with you on everything. But I like what you do. I like how you stand up. I'm going to support you.'"

Clinton won some applause for that answer, and Sanders commended her work as a senator, but he again slammed her for her opposition to breaking up big banks.

O'Malley also found an opportunity to contrast his outsider status to Clinton's Wall Street connections. "I believe that we actually need some new economic thinking in the White House," he said. "And I would not have Robert Rubin or Larry Summers with all due respect, Secretary Clinton, to you and to them, back on my council of economic advisers."

Sanders and O'Malley also teamed up against Clinton for her opposition to a federal $15 minimum wage. Clinton supports a $12 federal minimum wage, and she cited economist Alan Krueger's concern that $15 could be too high. A $15 minimum wage is "not a radical idea," Sanders said, adding, "I apologize to nobody about it."

O'Malley once again said he would "stop taking our advice from economists on Wall Street" (though Krueger is an academic, not a Wall Street banker).

The former governor also aggressively challenged Clinton on gun control, accusing her of "leading by polls [rather than] leading with principle."

"In 2008 you were portraying yourself as Annie Oakley," he charged.

Sanders and O'Malley also challenged Clinton on foreign policy, a prominent point of discussion following Friday's terrorist attacks in Paris.

Clinton said, "This cannot be an American fight, although American leadership is essential." That was enough of an opening for both candidates to critique her approach to the problem.

"This actually is America's fight," O'Malley said. "It cannot solely be America's fight. America is best when we work in collaboration with our allies....We must rise to this occasion in collaboration and with alliances to confront it."

Specifically, he called for a greater investment in human intelligence in order to craft a better strategy against ISIS.

Sanders used the opportunity to attack Clinton for voting for the Iraq war in 2002.

"I would argue that the disastrous invasion of Iraq, something that I strongly opposed, has unraveled the region completely, and led to the rise of Al Qaeda and to ISIS," he said.

Sanders added that he is a "bit more conservative" than Clinton when it comes to "regime change." He added, "These invasions, these toppling of governments, regime changes have unintended consequences."

While Clinton received the most scrutiny during the debate, she also managed to go on the offensive. She eviscerated Sanders' proposal to replace Obamacare with a Medicare-for-all system that relies largely on state implementation.

"I have to tell you, I would not want, if I lived in Iowa, Terry Branstad administering my health care," Clinton said of Iowa's Republican governor, prompting loud applause from the audience. "I think as Democrats, we ought to proudly support the Affordable Care Act, improve it, and make it the model that we know it can be."