Once upon a time, the Democratic National Committee had a plan for just four debates among the party's candidates for president. The general feeling among activists was that too many debates risked overexposing the candidates, their differences and the divisions within the party.

There had been too many debates, they felt, in 2008. It was just bad politics.

Now, some months later, the DNC has allowed eight debates, the latest in Miami on Wednesday night, sponsored by Univision and The Washington Post and broadcast on CNN. The first few debates were tucked into difficult time slots involving holidays or major sports events, but the latest have been relatively easy for the country as a whole to see.

The cast of contenders, originally five, has for more than a month now been down to two, one of whom will almost surely be the nominee. And judging by this latest clash, and the previous edition last Sunday night, it is easy to see why the DNC originally wanted the series to be shorter.

Sen. Bernie Sanders and former Secretary of State Hillary Clinton had at each other for two hours in each of these events, trading accusations and answering journalists' questions laden with accusations. Their various vulnerabilities and shortcomings have been clearly on display.

And while these last two debates were not nearly as raw and rivalrous as the most recent Republican debates, neither were they as collegial as the first two Democratic debates last fall.

Sanders ripped into Clinton for taking money from Wall Street in contributions and speaking fees. Clinton pounded Sanders for his vote against the 2007 comprehensive immigration reform bill negotiated by the late Massachusetts Sen. Ted Kennedy.

Again on Wednesday night, both candidates had plenty of partisans in the audience to provide cheers and applause, as well as occasional hoots and other expressions of disapproval for the media moderators.

Both candidates also had plenty of prepared material, much of which was already familiar. Sanders talked about the "rigged economy" and the "corrupt campaign finance system," the inequality of income (most of the income growth since the 2009 recession going to the top 1 percent) and the failure of capitalism to care about its workers.

Clinton talked about the need to extend President Obama's policies in virtually every area of governance, from the Affordable Care Act to the Dodd-Frank regulation of the financial sector. She defended her many contributions from the Wall Street world of finance in part by saying President Obama had taken Wall Street money, too.

But Clinton, like Sanders, did not defend the current administration's policies on deportation of recent immigrants without legal status. Both said they would end the deportation of children and the breaking up of families. It was a major area of agreement during the evening.

Asked for a specific commitment regarding the deportation of children, Clinton said: "I will not deport children, I will not deport children." She then proceeded to detail her priorities for other categories of people that might be subject to deportation, including violent criminals and those who plot terrorist attacks.

Sanders also disavowed child deportation, as well as the Obama administration's deportation policies, which have repatriated many thousands. He decried the very idea of mass deportations of the 11 million undocumented people now estimated to be in the U.S. While not contemplated by most of the policy community, just such a deportation is a cornerstone of the campaign of Republican presidential candidate Donald Trump.

Clinton called Trump's "very tall" wall on the Mexican border "a fantasy."

Given the setting, the sponsors and the audience, questions about immigration were a natural centerpiece for the debate. But the questioners also touched on the vacancy on the Supreme Court, the minimum wage and a separate set of vulnerabilities unique to each.

Sanders was asked about a 1985 video in which he criticized the U.S. for its interventionist policies in Latin America, particularly regarding Cuba. He had some praise, in the video, for the Castro regime on that island.

Sanders did not repudiate the views in the video and said the U.S. had overstepped the enforcement of the Monroe Doctrine regarding its security in the hemisphere.

Clinton was challenged regarding her handling of her private email server and also her allegedly misleading remarks to the families of U.S. personnel after the terrorist attack in Benghazi, Libya, in 2012. Both issues are fraught with political peril as both have been focal points for Republicans.

At one point, moderator Jorge Ramos of Univision asked her point-blank if she would withdraw from the race if indicted for the email arrangement.

"Oh for goodness ... " Clinton began. "That's not going to happen. I'm not even going to answer that question."

Clinton was also put on the spot to explain her loss this week in the Michigan primary, which polls had predicted she would win easily. She smiled and said she had still received more votes and more delegates than Sanders that day because Michigan was such a close vote and her victory in Mississippi had been overwhelming.

Next week, the two candidates again face off in voting in varied parts of the country: Florida, Illinois, Ohio, North Carolina and Missouri. While not as numerous as the states on "Super Tuesday," these five are among the most populous states in the country and therefore supply a comparable payoff in terms of delegates. Their cumulative impact could be even greater.

Clinton has already passed the halfway point in pursuit of the 2,383 delegates needed to be nominated in Philadelphia in July. But Sanders' narrow win in Michigan changed the narrative again and raised questions about the reliability of polls in other states where Clinton has had a lead.

The failure of the pollsters and media to foresee Sanders' win in Michigan, where he had been behind by as much as 20 points and more, has cast doubt on all the tools used by observers to foresee results in any election.

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