Republican frontrunners Donald Trump and Ben Carson were accused of peddling "fantasy" economic policies at their party's presidential debate on Wednesday, as less-known rivals managed to grab campaign limelight.
Upstart Senator Marco Rubio caused a stir at the third Republican primary debate, fighting off a frontal attack from his one-time ally Jeb Bush, then calling the presumptive Democratic nominee Hillary Clinton a liar.
The 10 White House candidates on stage were quick with the personal barbs, sign of the rising tension between the country's established politicians and political neophytes Trump and Carson, who top the polls less than 100 days before the first statewide nominating contests.
"Folks, we got to wake up," said Ohio Governor John Kasich, raising an alarm at the outset.
"We cannot elect somebody that doesn't know how to do the job. You have to pick somebody who has experience."
The language appeared clearly aimed at Trump, a real estate billionaire, and the retired neurosurgeon Carson, who were the targets of early brickbats as candidates ripped into their policy plans.
Kasich said the tax plans of both were "fantasy tax games" that would add trillions of dollars to the national debt.
Even the debate moderator joined in, asking Trump if he was running a "comic book version" of a campaign -- notably by promising to keep out immigrants with a wall on the Mexican border.
- French work week -
Millions of Americans were estimated to be tuning in to the sparring at an arena at the University of Colorado in Boulder.
As traditional candidates struggle to make headway against strong populist currents in their party, Carson appears to be catching up to Trump, overtaking him in the state of Iowa and edging ahead of him in one national poll released Tuesday.
With his star rising, Carson came under pressure to expand on his political platforms.
And the hyper-competitive Trump -- facing a slippage in his poll ratings -- seemed determined to reaffirm his position atop the Republican pyramid.
But with all eyes on the frontrunning pair, other candidates vied for the camera.
Jeb Bush, the son and brother of two presidents and a former Florida governor, launched a bold attack on his former protege Rubio, something he has been loath to do on the campaign trail.
"This is a six-year term, you should be showing up" for Senate votes, he told Rubio, who hails from the same state. "Is it a French work week? You get like three days where you have to show up? Just resign and let somebody else take the job."
But Bush otherwise failed to make a strong impression in the debate -- which many saw as a vital opportunity for him to reignite his flagging campaign.
Rubio fought off the challenge, and later drew applause when he skewered Clinton for her testimony about the 2012 Benghazi attacks before Congress last week, a performance praised by supporters and observers.
"It was the week she got exposed as a liar," Rubio said. "But she has her super PAC helping her out: the American mainstream media."
The line resonated and helped build the case that Rubio might be the most serious establishment challenger beyond Bush to go up against Trump and Carson, neither of whom have held elective office.
"Rubio won tonight with wit, good humor, great one liners and substance," tweeted Ari Fleischer, a White House press secretary during George W. Bush's presidency.
- 'Not a cage match' -
Ten candidates took the stage for the main event: Trump, Carson and Bush; Senators Rubio, Ted Cruz and Rand Paul; former Hewlett-Packard chief executive Carly Fiorina, who performed well at the previous debate; Arkansas ex-governor Mike Huckabee; Kasich and New Jersey Governor Chris Christie.
Cable network CNBC, which broadcast the primetime event, focused its debate on economic issues, including tax policy, federal spending and job growth.
But it also waded into other topics including the legalization of marijuana, and US gun laws, prompting Trump to repeat that he sometimes carries a weapon and would be comfortable with co-workers arming themselves.
"I think gun-free zones are a feeding frenzy for sickos," he said.
CNBC came under assault for its provocative questioning of candidates, several of whom called out the network for its lines of attack.
"This is not a cage match," Cruz said, defending his rivals.
And Republican National Committee chair Reince Priebus also weighed in, tweeting: "CNBC should be ashamed of how this debate was handled."
CNBC spokesman Brian Steel was unrepentant.
"People who want to be president of the United States should be able to answer tough questions," he said.
Trump is leading the RealClearPolitics average of opinion polls, with 26.8 percent, with Carson in second (22 percent), Rubio third (nine percent), Bush (seven) and Cruz (6.6).