Debate throws Democratic White House race open, Trump gloats

As the only black woman in the 2020 race, Harris already stands out, but she stole the show by attacking Biden's record on race relations, leaving him literally speechless.

Harris, a senator and former attorney general of California, pinned down Biden on his past opposition to school busing programs that forced integration of segregated school systems in the 1970s -- and Biden faltered.

"My time is up," he finally said. Although he'd meant that he had run out of the few seconds granted by moderators on the crowded debate stage, his words went viral on Twitter as a symbolic admission that he is a man of yesteryear in a party demanding radical change.

The radical spirit was on full display both Thursday and in the first debate Wednesday, showing the barriers facing a centrist like Biden on the way to the nomination.

While these issues are at the heart of what most agree are the deepest problems in the United States, they are also notorious ideological minefields and never have so many presidential candidates offered such uncompromising solutions.

Trump, on the other side of the world at the Japan G20 summit, gloated.

"All Democrats just raised their hands for giving millions of illegal aliens unlimited healthcare. How about taking care of American Citizens first!?" he tweeted.

"That's the end of that race!"

- Biden wounded or hardened? -

It's too early to say whether Biden, an affable, but gaffe-prone figure, will see his big polling lead melt away.

Trump certainly thinks so.

"Not a good day for Sleepy Joe or Crazy Bernie. One is exhausted, the other is nuts," Trump summarized with his characteristic insults on Twitter.

"Nonetheless, as frontrunner, Biden can look forward to many more attacks. Whether this sharpens Biden for the campaign against Trump (should he win the nomination) or deconstructs Biden on his way to losing the Democratic nod, we cannot guess."

- Harris prosecutes her case -

Despite an impressive resume and compelling personal story as a black woman who rose to the top, Harris, 54, has struggled to gain traction in a field dominated by two elderly white men -- Biden and Sanders -- and also featuring the intense Warren.

But then she began to question his history on the fraught issue, cornering him with the point that he'd once opposed busing.

In fact, busing was hugely controversial and not all opposition was motivated by wanting racial segregation.

But Harris, her voice quivering with emotion, had an ambush to complete.

"There was a little girl in California who was part of the second class to integrate her public schools and she was bused to school every day," she said to the hushed audience -- and to Biden.

"That little girl was me."

While the Florida debate was still going, the Harris campaign tweeted out that killer line with a picture of Harris as a schoolgirl in pigtails. A T-shirt bearing the same image went on sale immediately after.

- Taking on Trump -

So many Democrats are struggling to take on Trump that they are likely to fight each other for a long time first.

At the first debate on Wednesday, Trump's name was hardly mentioned.

Harris called Trump "the greatest national security threat to the United States" because of his rejection of warnings that the climate is in the midst of disastrous change.

Biden, seeking a recovery in his closing remarks, called for restoration of "the "soul" of the country after Trump "ripped it out."

"We have got to unite the United States of America," he said.