Miami(CNN) There were few softballs Wednesday night for Hillary Clinton and Bernie Sanders.
Clinton was asked whether she lied about Benghazi, whether she might be indicted over her emails and why she's seen as so untrustworthy. Sanders was pressed on comments he made in the mid-1980s about Fidel Castro and pushed to defend his 2007 vote against an immigration reform bill.
One day after Sanders' stunning win in Michigan, both candidates were on their game in their only debate before next Tuesday's critical votes in Florida, Ohio, Illinois and North Carolina.
Here are five takeaways from Wednesday night's debate, hosted by Univision and The Washington Post:
Clinton and Sanders both broke with the Obama White House and pledged to halt the deportations of undocumented immigrants who don't have criminal records.
"I can make that promise," Sanders said.
"I do not want to see them deported. I want to see them on a path to citizenship. That is exactly what I will do," Clinton said.
And both candidates dismissed Donald Trump's proposal to build a "big, beautiful wall" along the U.S.-Mexico border as bluster.
"As I understand him, he's talking about a very tall wall -- a beautiful tall wall, better than the Great Wall of China," Clinton said. "It's just fantasy."
It exposed a huge divide between the two parties: The Republican front-runner wants mass deportations. The Democratic contenders want no deportations at all. There's no middle ground anymore.
The evaporation of any sort of common ground on the issue of immigration helps explain the political plight of Republican candidates who have supported comprehensive reform measures, like Florida Sen. Marco Rubio and the departed South Carolina Sen. Lindsey Graham and former Florida Gov. Jeb Bush.
It also underscores why 2016's election is so much about motivating each party's base, rather than appealing to voters in the middle. The center didn't hold.
It was just days ago that Clinton, riding a wave of Super Tuesday victories, was dropping her attacks on Sanders, looking for ways to appeal to his supporters and casting her eyes on Republicans -- particularly Donald Trump.
CNN Reality Check: What's true and what's not from the debate
If she'd pivoted into general election mode, she went right back to the primary on Wednesday night.
On the heels of her loss in Michigan, Clinton was set on attacking Sanders on every question -- and most of the time, Sanders gave her the clash she wanted.
Clinton cast Sanders as an enemy of liberal icon Ted Kennedy, noting that he'd voted "against Ted Kennedy's immigration reform which he'd been working on for years before you ever arrived."
She hit him for opposing the auto bailout, even though fact-checkers had already pointed out that attack amounted to cherry-picking one item out of a much larger bank bailout bill -- using that issue to frame Sanders as someone so rigid in his ideology that he can't get things done.
"I'll tell you, it was a hard vote. A lot of the votes you make are hard votes," Clinton said. "But the fact is the money that rescued the auto industry was in that bill."
It was all a reminder that the Democratic presidential contest might not be anywhere near its end. Next Tuesday -- when Florida, North Carolina, Ohio, Illinois and Missouri vote -- was the day Clinton hoped to knock Sanders out. Now, Sanders poses a serious threat across the Midwest.
Sure, both candidates took their shots at Trump. Clinton called him "un-American" and Sanders called him someone who "insults Mexicans, who insults Muslims, who insults women, who insults African-Americans."
But Clinton's strategy was all about taking down Sanders.
Clinton made an unusually frank admission when she was pressed on why so many Americans find her untrustworthy.
"I am not a natural politician, in case you haven't noticed, like my husband and President Obama. So I have a view that I have to do the best I can," Clinton said, adding that she hopes "people will see I am fighting for them."
It was an effective moment -- an introspective acknowledgment from a politician who has struggled to project authenticity.
And it came right on the heels of a touching moment between Clinton and a woman who had discussed her hardships after her undocumented husband was deported.
"Please know how brave I think you are, coming here with your children to tell your story. This is an incredible act of courage that I'm not sure many people really understand. And I want you to know that," Clinton said.
It wasn't Bill Clinton personalizing the national debt in a 1992 debate by talking about the people he knows who have lost jobs. But Hillary Clinton doesn't necessarily need that knack for making the audience feel a struggling American's pain the way her husband did. She just has to make sure her economic message connects.
When Clinton attacks, she lays out a detailed, point-by-point case on why Sanders was wrong -- as if she were delivering the audience a PowerPoint presentation.
And then Sanders just changes the subject.
The simplicity of his overall message, and the skillfulness with which he deploys it when he's under attack, makes it difficult to land an effective blow on the Vermont senator.
READ: The origins of Sanders' ideology, in his own words
For the second straight Democratic debate, Clinton tried to hit Sanders for opposing the Export-Import Bank -- noting that he'd broken from Democrats and joined with hardline conservatives and Koch brothers-backed groups in voting to abolish it.
His rebuttal? "It is corporate welfare, and yes, I oppose corporate welfare."
She attacked his support for a Medicare-for-all health insurance system, arguing that Sanders' idea is too pie-in-the-sky and that Democrats just won a hard-fought battle for Obamacare.
"What Secretary Clinton is saying is that the United States should continue to be the only major country on earth that doesn't guarantee health care to all of its people," Sanders shot back, getting the crowd roaring with a rant about prescription drug companies' hold on Capitol Hill.
It's not just a stylistic difference. Sanders' policy positions are uncompromising and Clinton's aren't.
Sanders showed what an asset that can be on the debate stage for most of the night -- and then what a liability it can be, if not among Democrats then in the general election, in the closing minutes.
He was shown a video of himself in the 1980s and asked about the differences between socialism and communism. Sanders answered that he was opposing U.S. intervention in Latin America.
The episode opened the door for an attack from Clinton's campaign over Sanders' refusal to disavow the Castros -- whom he had praised decades earlier -- and served as a reminder that his activist past is fertile ground for attacks.
It was the most tedious unloading of opposition research on a presidential debate stage yet this year.
The candidates even seemed to sense it -- tip-toeing into their attacks initially before throwing their best punches.
Clinton hit Sanders for his vote against a 2007 comprehensive immigration reform bill.
"Just think -- imagine where we would be today if we had achieved comprehensive immigration reform nine years ago. Imagine how much more secure families would be in our country no longer fearing the deportation of a loved one, no longer fearing that they would be found out," she said.
Sanders responded by blasting that 2007 measure's guest worker provisions, saying that workers were abused "and if they stood up for their rights, they would be thrown out of the country. Of course that type of effort leads to a race to the bottom for all of our people."
He also hit Clinton for opposing driver's licenses for undocumented immigrants, and Clinton hit Sanders for voting in 2006 to protect a vigilante border group, the "Minutemen."
It felt like New Jersey Gov. Chris Christie -- famous for bashing his Senate colleagues' tussles over the exact details of bills and amendments on the Republican debate stage -- might have been about to dart onto stage to shout them both down.
Their debates about old bills were all beside the point when it comes to where the candidates stand in 2016. They largely agree on immigration-related issues. In fact, their real target within the Democratic Party is Obama, who's been much more aggressive about deporting undocumented immigrants than Sanders and Clinton say they'd be.