4. Some issues came up that hadn't and others got attention in different ways
Climate change was a focus earlier than in past debates.
And other topics, which have received little-to-no attention, also came up — everything from trade and China to Muslim Uighurs and Israel and the Palestinian territories.
It's a reminder that there are lots of things a president has to deal with — and often has more control over — than many of the topics that dominate presidential campaigns.
5. Health care didn't come up until late
One topic that came up later than usual (10:06 p.m. ET, more than two hours into the debate) was health care. The candidates have debated health care ad nauseam in prior debates, but Thursday night's had a new wrinkle – whether the candidates calling for big change would be in favor of less sweeping measures if Medicare for All failed to pass Congress as a replacement for private health insurance .
The question was directed to Sanders, and he wouldn't say. "We're going to have the American people behind us; we will have the Congress behind us," Sanders insisted.
Biden said he didn't think that was "realistic." And that highlights the real fracture in the Democratic Party primary — the purists versus the pragmatists.
Klobuchar chimed in to defend both Biden and herself. "I think you can be progressive and practical at the same time," she said, adding that Sanders' fight wasn't really with her or Biden, but with new House members from moderate districts and with Andy Beshear, the new Democratic governor of conservative Kentucky, who wants to build on Obamacare.
"If you want to cross a river over some troubled waters," Klobuchar said, "you build a bridge, you don't blow one up."
Notably, the other candidate in favor of Medicare for All stayed silent for most of the exchange. When Warren did speak up, she answered the moderator's original question and noted some less-sweeping health care measures she supports and believes could pass Congress.
Last month, Warren walked back her full-throated support of Medicare for All, endorsing an interim step – a Medicare for All "option." It's a critical change for Warren. It makes her look more practical, and the move represents a pivot and admission that her full and uncompromising support of Medicare for All was hurting her presidential bid. After all, Medicare for All as a full replacement of private health insurance is much less popular than if presented as an option.
6. Democrats had to deal with a less-diverse stage
With Sen. Kamala Harris of California dropping out of the race and Sen. Cory Booker of New Jersey and former Obama housing secretary Julián Castro not qualifying for the debate, this was not only the smallest number of candidates on a Democratic stage this cycle, but it was also the least diverse.
"It's both an honor and disappointment to be the lone candidate of color on the stage tonight," entrepreneur Andrew Yang said, adding that while he was called names for being Asian growing up, blacks and Latinos "have something much more powerful working against them than words. They have numbers."
Yang noted that African Americans and Latinos have only a fraction of whites' net worth. "These are the numbers that define race in this country," he said. "And the question is, 'Why am I the lone candidate of color on this stage?' Fewer than 5% of Americans donate to political campaigns. You know what you need to donate to political campaigns? Disposable income."
The other candidates on stage tried to point out, in different ways, their own claims to diversity. Buttigieg noted that he is the son of an immigrant father and at least twice made reference to being gay.
Warren and Klobuchar highlighted, in sometimes humorous ways, that they were the only women on stage. Warren, 70, was asked about the fact that if elected, she would be the oldest person to take office as president (a distinction currently held by Trump; Biden and Sanders would be older still).
"I'd also be the youngest woman ever inaugurated," she quipped.
And Klobuchar said she once pointed out to Trevor Noah of The Daily Show, "in the history of the Senate, there was something like 2,000 men and only 50 women in the whole history." (The numbers are 1,926 and 56, according to Senate and House historians.)
Noah's response, Klobuchar said: " 'If a nightclub had numbers that bad, they would shut it down.' "
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