at last night's "PBS NewsHour"/Politico debate jockeying to become the Democrat with a chance

to unseat President Trump.

They jousted over policy, political influence, and who among them was the best equipped to

take on the president in 2020.

John Yang begins our look.

JOHN YANG: The tone of the "PBS NewsHour"/Politico debate turned on a dime from civil to contentious.

The spark?

Massachusetts Senator Elizabeth Warren calling out South Bend, Indiana, Mayor Pete Buttigieg,

over fund-raising, specifically a fund-raiser he attended this past weekend hosted by Napa

Valley winery owners.

SEN.

ELIZABETH WARREN (D-MA), Presidential Candidate: the mayor just recently had a fund-raiser

that was held in a wine cave full of crystals and served $900-a-bottle wine.

Think about who comes to that.

He had promised that every fund-raiser he would do would be open door, but this one

was closed door.

We made the decision many years ago that rich people in smoke-filled rooms would not pick

the next president of the United States.

PETE BUTTIGIEG (D), Presidential Candidate: This is the problem with issuing purity tests

you cannot yourself pass.

(CHEERING AND APPLAUSE)

PETE BUTTIGIEG: If I pledge -- if I pledge never to be in the company of a progressive

Democratic donor, I couldn't be up here.

Senator, your net worth is 100 times mine.

JOHN YANG: Buttigieg and Warren are competing for the same supporters: college-educated

white voters.

The mayor also clashed with Minnesota Senator Amy Klobuchar, who contrasted her election

successes with his failures.

SEN.

AMY KLOBUCHAR (D-MN), Presidential Candidate: We should have someone heading up this ticket

that has actually won and been able to show that they can gather the support that you

talk about of moderate Republicans and independents, as well as a fired-up Democratic base, and

not just done it once; I have done it three times.

I think winning matters.

PETE BUTTIGIEG: If you want to talk about the capacity to win, try putting together

a coalition to bring you back to office with 80 percent of the vote as a gay dude in Mike

Pence's Indiana.

(CHEERING AND APPLAUSE)

SEN.

AMY KLOBUCHAR: Again, I would -- Mayor, if you -- if you had won in Indiana, that would

be one thing.

You tried and you lost by 20 points.

JOHN YANG: Another fault line?

Health care.

Vermont Senator Bernie Sanders supports Medicare for all, while former Vice President Joe Biden

wants to expand a public option.

JOSEPH BIDEN (D), Presidential Candidate: Sixteen percent of the American public is

on Medicare now and everybody has a tax taken out of their paycheck now.

Tell me, you're going to add 84 percent more and there's not going to be higher taxes?

At least before he was honest about it.

SEN.

BERNIE SANDERS (I-VT), Presidential Candidate: Joe...

JOSEPH BIDEN: It's going to increase personal taxes.

There are going to be...

SEN.

BERNIE SANDERS: That's right.

We are going to increase personal taxes.

But we're eliminating premiums, we're eliminating co-payments, we're eliminating deductibles,

we're eliminating all out-of-pocket expenses, and no family in America will spend more than

$200 a year on prescription drugs.

JOHN YANG: Two lower-tier candidates who made last night's more select debate stage sought

to take advantage of the platform.

Tech entrepreneur Andrew Yang noted that he was the only candidate of color in the debate.

ANDREW YANG (D), Presidential Candidate: I grew up the son of immigrants, and I had many

racial epithets used against me as a kid.

But black and Latinos have something much more powerful working against them than words.

They have numbers.

The average net worth of a black household is only 10 percent that of a white household.

Fewer than 5 percent of Americans donate to political campaigns.

You know what you need to donate to political campaigns?

Disposable income.

I guarantee, if we had a freedom dividend of $1,000 a month, I would not be the only

candidate of color on this stage tonight.

JOHN YANG: Billionaire activist Tom Steyer discussed race in the context of President

Trump's immigration policies.

TOM STEYER (D), Presidential Candidate: I think it's important to note that this president

is not against immigration.

He's against immigration by nonwhite people.

This is a racial argument by a racist president who's trying to divide us and who's vilifying

people.

It's absolutely wrong.

And it's led him to break the laws of humanity in our name.

JOHN YANG: The night also featured the most in-depth discussion of foreign policy so far

this cycle, from China's human rights record.

JOSEPH BIDEN: A million Uyghurs, as you pointed out, Muslims, are in concentration camps.

That's where they are right now.

They're being abused.

They are in concentration camps.

JOHN YANG: To the Israeli-Palestinian conflict.

SEN.

BERNIE SANDERS: What U.S. foreign policy must be about is not just being pro-Israel.

We must be pro-Palestinian as well.

JOHN YANG: Despite lively disagreements on policy, the candidates didn't lose sight of

one issue that unites them.

PETE BUTTIGIEG: This is our chance, this is our only chance to defeat Donald Trump.

JOHN YANG: A point that polls show Democratic voters also in strong agreement.

For the "PBS NewsHour," I'm John Yang.