Democratic White House front-runner Elizabeth Warren has been fiercely attacked by rivals in a live TV debate.
They accused the Massachusetts senator of dodging a question on whether she would raise taxes.
Twelve White House hopefuls squared off in the primetime forum, with two other front-runners also under pressure.
Joe Biden hit back against Republican personal attacks, while Bernie Sanders sought to allay doubts about his health after a heart attack this month.
Snapping at the heels of the pack leaders, South Bend, Indiana, Mayor Pete Buttigieg, California Senator Kamala Harris and Minnesota Senator Amy Klobuchar came out fighting on Tuesday night.
Also on stage were New York entrepreneur Andrew Yang, former Texas congressman Beto O'Rourke, New Jersey Senator Cory Booker, former Obama housing secretary Julian Castro, Hawaii congresswoman Tulsi Gabbard and billionaire activist Tom Steyer.
The forum in the electoral battleground state of Ohio was the most crowded so far in the Democratic race.
Time is running out for the lower-tier contenders to make an impression. The Democratic White House race officially begins with the Iowa caucuses on 3 February.
The pack will be whittled down in state-by-state votes until a final candidate is crowned at the party convention next July.
He or she will take on President Donald Trump, a Republican, in the November 2020 election.
How did Warren find herself under attack?
Ms Warren found a bullseye on her back after surging to the top of the field over the past two months.
Both Mr Sanders, a Vermont senator, and Ms Warren favour free healthcare for all Americans.
But unlike Mr Sanders, Ms Warren has repeatedly avoided stating explicitly whether her version of "Medicare for All" would raise taxes on working families.
She was pressed on the issue by debate moderators and replied that she would not sign any bill that hiked costs on the middle class.
Mr Buttigieg rounded on her, saying: "You heard it tonight – a yes or no question that didn't get a yes or no answer.
"This is why people here in the Midwest are so frustrated with Washington in general and Capitol Hill in particular."
Even Ms Warren's progressive ally Mr Sanders took a veiled jab, saying: "I do think it is appropriate to acknowledge that taxes will go up."
Ms Klobuchar pounced: "At least Bernie's being honest here and saying how he's going to pay for this and taxes are going to go up.
"And I am sorry, Elizabeth, but you have not said that, and I think we owe it to the American people to tell them where we are going to send the invoice."
Mr Biden took a pop at both Ms Warren and Mr Sanders.
"Both are being vague on the issue of Medicare for All," he said. "Now look, here's the deal, come on, it costs 30 trillion dollars!"
Ms Warren did not appear flustered under the repeated attacks, focusing on her policy prescriptions for ending income inequality.
Ms Harris, meanwhile, repeatedly challenged Ms Warren to back her call for Twitter to delete Mr Trump's account for incendiary tweets.
Ms Warren replied: "I don't just wanna push Donald Trump off Twitter, I want to push him out of the White House."
What about the Hunter Biden story?
Mr Biden was asked about Mr Trump's unsubstantiated claims that the former US vice-president improperly tried to aid his son Hunter Biden's business interests in Ukraine.
"My son did nothing wrong," replied Mr Biden, whose once commanding lead in opinion polls has been slipping. "I did nothing wrong."
He was pressed by the debate moderator on whether he made a mistake while he was the Obama administration's point man on Ukraine by allowing his son to serve on the board of a Ukrainian gas company.
Mr Biden replied that he never discussed "a single thing" about Ukraine with his son. Meanwhile, his rivals refrained from attacking him about it.
It was the first debate since congressional Democrats launched an impeachment inquiry into Mr Trump's efforts to pressure Ukraine to investigate Joe Biden.
Every candidate on stage backed the investigation, which may seek to remove the president from office, railing against Mr Trump's "criminality" and "corruption".
Warren's weak spot
Elizabeth Warren knew she was going to take some shots now that she's reached the top of the pack. She was not wrong.
Once again, her refusal to acknowledge that her universal healthcare plan raises some taxes was targeted by the more moderate candidates. She doggedly refused to be pinned down, but for once the attacks – particularly from Pete Buttigieg and Amy Klobuchar – felt like they had more bite. She can keep dancing, but her weakness here isn't going away – and could become a real problem in a general election.
Despite this, she had her share of memorable lines. Her early support for Donald Trump's impeachment helped give her answer on the topic – that "impeachment is the way that we establish that no one will be able to break the law over and over again without consequences" – extra punch. Her defence of a wealth tax, saying that she prefers to invest in a generation of Americans and not "protect billionaires", will resonate with many Democrats.
And when Joe Biden spoke about his efforts to get votes for Ms Warren's financial reform legislation in 2009, she pointedly praised Barack Obama – and not the vice-president – for his support. It was a subtle way of prying Mr Biden away from his embrace of Mr Obama's political legacy.
How did age come up?
Mr Sanders was closely watched for signs of fatigue in the three-hour debate after he suffered a heart attack earlier this month.
The oldest contender at 78, Mr Sanders has dropped into third place in the polls.
"I'm healthy," the self-described democratic socialist told a moderator who questioned his fitness. "I'm feeling great."
In a touching gesture, he added: "Let me take this moment, if I might, to thank so many people from alRead More – Source