Republican outsider front-runners Ben Carson and Donald Trump came under fire at the outset of the party's third presidential debate Wednesday night, as the moderators and some of their opponents pushed for details of their tax and budget proposals and raised questions about their inexperience in government.

Ohio Gov. John Kasich, who before the debate had hinted that he would be more aggressive, warned that his party was on the verge of "picking someone who perhaps cannot do this job," and after Carson defended his tax rate, exploded. "This is the fantasy that I talked about at the beginning," he said.

Kasich also attacked Trump for his proposal to deport an estimated 11 million illegal immigrants. Trump immediately shot back at Kasich, zeroing in on his tenure as an investment banker in between his terms as a member of Congress and Ohio governor. "He was a managing general partner with Lehman Brothers when it went down the tubes," Trump said.