Donald Trump slips in polls after Republican debate

Frontrunner Donald Trump has slipped in the polls after this week's Republican presidential debate while former Hewlett-Packard CEO Carly Fiorina shot to second place, according to a new poll.

The CNN/ORC poll released on Sunday had Trump still leading the field, with 24 per cent of Republican voters supporting him, but that total was down eight percentage points from earlier this month.

"The only poll that matters is the big one. You know that one. It's going to be the election," Trump told CNN's "State of the Union" in a telephone interview, saying he was surprised by the results.

Fiorina gained after a strong debate performance in which she icily skewered the brash real estate mogul for disparaging her looks in comments reported by Rolling Stone magazine.

"I think women all over this country heard very clearly what Mr Trump said," Fiorina said in Wednesday night's debate.

The CNN poll had her at 15 per cent, just ahead of Ben Carson, the mild-mannered retired brain surgeon who in recent weeks has been Trump's closest challenger.

Trump said Fiorina had had a "good night" but said she benefited from easy questions.

"You gave her some beautiful softballs," he told "State of the Union" host Jake Tapper, who moderated the Republican debate.

In fourth place, behind the three "outsider" candidates, Florida Senator Marco Rubio also jumped significantly, with eight percentage point spurt to 11 per cent.

He downplayed the results Sunday on ABC's "This Week," though, saying, "These polls don't really mean anything at this stage ... They're deciding who gets on the stage. They're not going to decide this election."

He attributed the outsider candidates' leads to a "disconnect" between Washington and the populace "that has never been larger than it is now."

"You saw some of it reflected in the debate the other day. It's not limited to the politicians, it's also about the media," Rubio said, arguing that the three-hour debate did not discuss issues relevant to working-class Americans.