Three polls show post-debate Trump lead

Donald Trump leads with 17 percent of the vote among likely Republican caucus-goers in Iowa, though the reality TV businessman fared a little worse among those who had watched last week's Fox News debate, according to a new poll from Suffolk University released Tuesday.

Among all Iowa respondents, Gov. Scott Walker of neighboring Wisconsin was running second at 12 percent; Florida Sen. Marco Rubio had 10 percent; retired neurosurgeon Ben Carson was drawing support of 9 percent. Sen. Ted Cruz of Texas and businesswoman Carly Fiorina, who was praised for her strong performance in the undercard debate for lower-polling candidates, were tied at 7 percent.

Jeb Bush, the former Florida governor, polled at 5 percent, followed by Ohio Gov. John Kasich (3 percent), while former Arkansas Gov. Mike Huckabee, Sen. Rand Paul (R-Ky.), and New Jersey Gov. Chris Christie each had  2 percent support. Six other candidates received 1 percent or less, while 20 percent of voters were undecided.

"It appears that Donald Trump's lead is strong so long as the number of active opponents remains above a dozen," said David Paleologos, director of the Suffolk University Political Research Center in Boston. "If the Republican field were winnowed down to five or six candidates, Trump's 17 percent probably wouldn't be enough to win in Iowa, as polling indicates that his further growth has limitations. The long-shot candidates staying in the race help keep Trump on top—at least for now."

The race was closer among viewers of last Thursday's debate: Trump and Walker were tied at 14 percent, with Rubio (11 percent), Carson and Fiorina (tied at 10 percent), and Cruz (9 percent) close behind. However, among likely caucus voters who skipped watching the Fox News debate, Trump (21 percent) led Carson (10 percent) by a wider margin, with Rubio and Walker tied at 8 percent.

When viewers were asked about Trump after seeing him debate, 55 percent said they were less comfortable with him as a candidate for president, and 23 percent said they were more comfortable.

Suffolk's statewide survey was based on live telephone interviews with 500 Iowa Republican voters who said they were likely to caucus, conducted August 7 through Aug. 10. Results are subject to a margin of sampling error of plus or minus 4.4 percentage points (larger for subgroups).

Two national polls released before the Suffolk survey indicated Trump's bombastic debate performance, and his battles with Fox News moderator Megyn Kelly in the wake of it – including his suggestions that she was hormonal when she questioned him about misogynistic comments – have not yet dented his lead.

In a Reuters/Ipsos survey, released Monday afternoon, Trump is supported by 24 percent of Republican voters, double the 12 percent who back Bush. No other GOP candidate gets above 8 percent support in the poll.

And a poll released late Sunday by NBC News and the University of Pennsylvania Program on Opinion Research pegged Trump's support at 23 percent nationally.  Cruz, an ally of the tea party, was running second at 13 percent.  Carson was third at 11 percent in the NBC News poll.