2nd Democratic Presidential Debate: 7 Moments That Mattered

The Democratic presidential hopefuls faced off in the wake of the Paris attacks.

Held in the critical early caucus state of Iowa and hosted by CBS News, here are seven moments that mattered at tonight’s debate:

1. Candidates Go to War Over Wall Street

The Democratic presidential debate featured the most heated exchange yet between the candidates over Clinton’s ties to Wall Street.

“Not good enough,” Bernie Sanders said of her promise not to be influenced by Wall Street donors.

Clinton said Sanders was looking to “impugn my integrity,” and cast her support for Wall Street as a senator from New York as a way to rebuke terrorists who attacked Lower Manhattan on 9/11.

“It was good for the economy, and it was a way to rebuke the terrorists who had attacked our country,” she said.

She added: “My proposal is tougher, more effective and more comprehensive because I go after all of Wall Street, not just the big banks.”

Martin O’Malley also got in on the action – with economic populism hitting Clinton literally from all sides on stage.

2. Clinton and O’Malley Spar Over ‘American Fight’

With news of the Paris attacks not even 24 hours old, CBS News moderator John Dickerson kicked off the debate with a pointed question for Hillary Clinton: “Won't the legacy of this administration, which you were a part of, won't that legacy be that it underestimated the threat from ISIS?”

Clinton drew contrast with President Obama’s comment Thursday that ISIS had been contained, saying, “It cannot be contained. It must be defeated.”

Clinton then stressed, “This cannot be an American fight, although American leadership is essential.”

But former Maryland Gov. Martin O’Malley said he disagrees with Clinton. “This actually is America's fight,” he said. “It cannot solely be America's fight. America is best when we work in collaboration with our allies,” O’Malley said. “We do have a role in this. Not solely ours, but we must work collaboratively with other nations.”

3. Sanders and Clinton Spat Over Iraq War Vote

A disagreement over a 2002 U.S. Senate vote to invade Iraq came center stage tonight.

“I don't think any sensible person would disagree that the invasion of Iraq led to the massive level of instability we are seeing right now,” said Sanders, who voted against the war in Iraq.

“I think that was one of the worst foreign policy blunders in the modern history of the United States.”

But Clinton responded by listing previous terrorist attacks in the history of the United States.

“I have said the invasion of Iraq was a mistake,” she said. “But I think if we're ever going to really tackle the problems posed by jihadi extreme terrorism, we need to understand it and realize that it has antecedents to what happened in Iraq.”

4. ‘Your Damn Emails’ Returned

Asked about whether it was an important issue, Sanders answered. “I was sick and tired of Hillary Clinton's e-mail. I am still sick and tired of Hillary Clinton's e-mails.”

Like he did in the previous debate, he said he wanted to talk about the middle class, income inequality, and paid family leave.

“We've gotten off the Hillary's emails, good,” he said. “Let's go to the major issues facing America.”

Clinton was asked for her response and she quipped: “I agree completely. I couldn't have said it better myself.”

Dickerson later asked Clinton to assure Democrats who may worry about "another shoe dropping" with the email scandal. She answered: "I think after 11 hours, that's pretty clear, yes?”

5. Clinton Refuses to Use Characterization of ‘Radical Islamists’

“I don't think we're at war with Islam. I don't think we're at war with all Muslims. I think we're at war with jihadists,” Clinton said in answering whether she’d characterize the ISIS attackers on Paris as “radical Islamists.”

Clinton would not commit, invoking the moment that former president George W. Bush visited a mosque after 9/11 and declared “Islam is peace.”

“If they hear people running for president who basically shortcut it to say we are somehow against Islam, that was one of the real contributions, despite all the other problems, that George W. Bush made after 9/11 when he basically said after going to a mosque in Washington,” Clinton said.

“We are not at war with Islam or Muslims. We are at war with violent extremism. We are at war with people who use their religion for purposes of power and oppression...But I don't want us to be painting with too broad a brush.”

Her comments sparked an outcry from Republicans presidential candidates, including Jeb Bush. Republicans have been categorizing ISIS and other terror organizations as “radical Islamists,” and have railed against the Obama administration and Democrats for not characterizing it as such.

Yes, we are at war with radical Islamic terrorism. #DemDebate

— Jeb Bush (@JebBush) November 15, 2015,

.@HillaryClinton how can we defeat our enemy if we cannot identify who they are and what motivates them? #DemDebate #RadicalIslam

— Rick Santorum (@RickSantorum) November 15, 2015,

You're all grown up now. You can do it. Three words. Ten syllables. Say it with me: "Radical Islamic terrorism." #DemDebate

— Gov. Mike Huckabee (@GovMikeHuckabee) November 15, 2015,

We need a President who will see and speak and act on the truth...Hillary Clinton will not call this Islamic terrorism. I will.

— Carly Fiorina (@CarlyFiorina) November 15, 2015

6. Candidates Draw Lines on Higher Minimum Wage

Sanders and O’Malley staked out their positions on the minimum wage to the left of Hillary Clinton, but the former secretary of state held her ground.

“I believe that over the next few years, not tomorrow, but over the next few years we have got to move the minimum wage to a living wage, 15 bucks an hour,” Sanders said. “And I apologize to nobody for that.”

O’Malley has also called for a $15 per hour minimum wage.

But Clinton said that she supported a lower hike in the minimum wage, after moderators cited a warning from economist Alan Krueger on potential job losses with a large increase.

“I do take what Alan Krueger said seriously. He is the foremost expert in our country on the minimum wage and what its effects are,” she said. “That is why I support a $12 national federal minimum wage.”

The candidates then began talking over each other when Clinton mentioned raising wages higher in specific, high cost of living areas. “It's what happened in Governor O'Malley's state,” she said.

“Didn't just happen,” he fired back.

7. Presidential Candidates Like Ike

Thought about President Dwight D. Eisenhower recently? Well, presidential candidates on both sides of the aisle are thinking about Ike.

Tonight, Sanders was asked how high would the tax rate go under those who earn the most in this country.

“We haven't come up with an exact number yet but it will not be as high as the number under Dwight D. Eisenhower, which was 90 percent,” Sanders said. “But it will be I'm not that much of a socialist compared to Eisenhower.”

During Eisenhower’s administration, a Republican, a 92 percent marginal income tax rate for top earners in the United States remained from Harry S. Truman’s previous administration. At the time, the highest tax bracket was earners over $400,000.

In 1954, still under Eisenhower, the 92 percent marginal rate decreased to 91 percent.

This is the second Eisenhower reference in the past week by a presidential candidate. Tuesday night at the GOP debate, Donald Trump mentioned the 34th president, saying he would model his immigration plan to round up and deport the 11 million undocumented immigrants living in the United States after Eisenhower’s presidential directive.

The controversial program did deport an estimated 1 million Mexican undocumented immigrants with tactics that have been called inhumane.

ABC News' Veronica Stracqualursi and Rick Klein contributed to this story.

Yes, we are at war with radical Islamic terrorism. #DemDebate

.@HillaryClinton how can we defeat our enemy if we cannot identify who they are and what motivates them? #DemDebate #RadicalIslam

You're all grown up now. You can do it. Three words. Ten syllables. Say it with me: "Radical Islamic terrorism." #DemDebate

We need a President who will see and speak and act on the truth...Hillary Clinton will not call this Islamic terrorism. I will.

6. Candidates Draw Lines on Higher Minimum Wage

Sanders and O’Malley staked out their positions on the minimum wage to the left of Hillary Clinton, but the former secretary of state held her ground.

“I believe that over the next few years, not tomorrow, but over the next few years we have got to move the minimum wage to a living wage, 15 bucks an hour,” Sanders said. “And I apologize to nobody for that.”

O’Malley has also called for a $15 per hour minimum wage.

But Clinton said that she supported a lower hike in the minimum wage, after moderators cited a warning from economist Alan Krueger on potential job losses with a large increase.

“I do take what Alan Krueger said seriously. He is the foremost expert in our country on the minimum wage and what its effects are,” she said. “That is why I support a $12 national federal minimum wage.”

The candidates then began talking over each other when Clinton mentioned raising wages higher in specific, high cost of living areas. “It's what happened in Governor O'Malley's state,” she said.

“Didn't just happen,” he fired back.

7. Presidential Candidates Like Ike

Thought about President Dwight D. Eisenhower recently? Well, presidential candidates on both sides of the aisle are thinking about Ike.

Tonight, Sanders was asked how high would the tax rate go under those who earn the most in this country.

“We haven't come up with an exact number yet but it will not be as high as the number under Dwight D. Eisenhower, which was 90 percent,” Sanders said. “But it will be I'm not that much of a socialist compared to Eisenhower.”

During Eisenhower’s administration, a Republican, a 92 percent marginal income tax rate for top earners in the United States remained from Harry S. Truman’s previous administration. At the time, the highest tax bracket was earners over $400,000.

In 1954, still under Eisenhower, the 92 percent marginal rate decreased to 91 percent.

This is the second Eisenhower reference in the past week by a presidential candidate. Tuesday night at the GOP debate, Donald Trump mentioned the 34th president, saying he would model his immigration plan to round up and deport the 11 million undocumented immigrants living in the United States after Eisenhower’s presidential directive.

The controversial program did deport an estimated 1 million Mexican undocumented immigrants with tactics that have been called inhumane.

ABC News' Veronica Stracqualursi and Rick Klein contributed to this story.