Washington (CNN) Donald Trump has a significant lead in the race to win over likely Iowa caucus-goers, according to the first CNN/ORC poll in the state this cycle.

Trump tops the field with 22% and is the candidate seen as best able to handle top issues including the economy, illegal immigration and terrorism. He's most cited as the one with the best chance of winning the general election, and, by a wide margin, as the candidate most likely to change the way things work in Washington.

Retired neurosurgeon Ben Carson follows Trump in overall preference with 14%, bumping Wisconsin Gov. Scott Walker, who had held the top spot in most recent public polling in Iowa, down to third place with 9%. Walker is nearly even with a slew of other candidates.

Previous public polls had found Carson with around 10% support, but most were released before last week's debate. A Suffolk University poll of Iowa Republicans released Tuesday found Carson's closing remarks to be the most memorable moment for those who watched the prime time debate.

Texas Sen. Ted Cruz follows the top three at 8%, with businesswoman Carly Fiorina and former Arkansas Gov. Mike Huckabee both at 7%. Former Florida Gov. Jeb Bush is tied at 5% with senators Rand Paul and Marco Rubio. The rest of the field stands at 3% or less.

Two-thirds of Iowa Republicans who are likely to attend the caucus say they're still trying to decide whom to support. Among the 34% who say they have made up their mind or are leading toward a candidate, Trump's lead grows, and the top of the field shifts. Among that group, 33% back Trump, 14% Carson, 11% Fiorina, and 9% each back Paul and Walker. Cruz follows at 7%, and all others have less than 5% support.

But Trump's advantages are not universal. He faces a large gender gap: While holding a 15-point lead over his nearest competitor among men (27% Trump to 12% Walker, Carson at 10%), he trails among women (20% back Carson, 15% Trump, and 11% support Fiorina). He runs behind Carson and about even with Walker and Cruz among those who describe themselves as "very conservative" (25% Carson, 15% each Cruz and Walker, 12% Trump), and he runs even with Carson among evangelical Christians (18% each Trump and Carson, 12% Cruz, 11% Huckabee, 10% Walker).

Both evangelical Christians and those who call themselves very conservative make up a substantial share of Iowa caucus-goers. According to entrance polls conducted for CNN, half of caucus attendees considered themselves "very conservative" in 2012, while born-again Christians were 57% of participants. Forty-three percent of 2012 Republican caucus attendees were women.

Trump's support in Iowa rests on perceptions that he would do the best job handling several top issues and that he is most electable. He tops the list by wide margins when GOP caucus-goers are asked which candidate they trust most to handle the economy, illegal immigration and terrorism. And Trump holds his biggest advantage as the candidate who "is most likely to change the way things work in Washington," 44% say Trump can do that, no other candidate hits double-digits.

But while Trump falters somewhat on representing the values of Republicans, no clear leader emerges on that question, with nine candidates at 5% or higher: 14% Carson, 12% Trump, 11% Huckabee, 10% Cruz, 9% Walker, 6% each Bush and Paul, and 5% each Fiorina and Jindal. And he falls well below the lead when voters are asked which candidate would best handle abortion; 17% each say Carson and Huckabee would be best on that score, 7% each choose Bush and Trump, 6% each Cruz, Paul and Walker, and Rubio stands at 5%.

Photos: Who's running for president? Photos: Who's running for president? Ted Cruz, Donald Trump, John Kasich, Hillary Clinton and Bernie Sanders, Hide Caption 1 of 6 Photos: Who's running for president?



"So, ladies and gentlemen, I am officially running for president of the United States, and we are going to make our country great again," Trump told the crowd at his announcement. Businessman Donald Trump announced June 16 at his Trump Tower in New York City that he is seeking the Republican presidential nomination. This ends more than two decades of flirting with the idea of running for the White House."So, ladies and gentlemen, I am officially running for president of the United States, and we are going to make our country great again," Trump told the crowd at his announcement. Hide Caption 2 of 6 Photos: Who's running for president?



"These are all of our stories," Cruz told the audience at Liberty University in Virginia. "These are who we are as Americans. And yet for so many Americans, the promise of America seems more and more distant." Sen. Ted Cruz of Texas has made a name for himself in the Senate, solidifying his brand as a conservative firebrand willing to take on the GOP's establishment. He announced he was seeking the Republican presidential nomination in a speech on March 23."These are all of our stories," Cruz told the audience at Liberty University in Virginia. "These are who we are as Americans. And yet for so many Americans, the promise of America seems more and more distant." Hide Caption 3 of 6 Photos: Who's running for president? Ohio Gov. John Kasich joined the Republican field July 21 as he formally announced his White House bid.



"I am here to ask you for your prayers, for your support ... because I have decided to run for president of the United States," Kasich told his kickoff rally at the Ohio State University. Hide Caption 4 of 6 Photos: Who's running for president?



"Everyday Americans need a champion, and I want to be that champion -- so you can do more than just get by -- you can get ahead. And stay ahead," she said in her announcement video. "Because when families are strong, America is strong. So I'm hitting the road to earn your vote, because it's your time. And I hope you'll join me on this journey." Hillary Clinton launched her presidential bid on April 12 through a video message on social media. The former first lady, senator and secretary of state is considered the front-runner among possible Democratic candidates."Everyday Americans need a champion, and I want to be that champion -- so you can do more than just get by -- you can get ahead. And stay ahead," she said in her announcement video. "Because when families are strong, America is strong. So I'm hitting the road to earn your vote, because it's your time. And I hope you'll join me on this journey." Hide Caption 5 of 6 Photos: Who's running for president?



"This great nation and its government belong to all of the people and not to a handful of billionaires, their super PACs and their lobbyists," Sanders said at a rally in Vermont on May 26. Sen. Bernie Sanders , an independent from Vermont who caucuses with Democrats, announced his run in an email to supporters on April 30. He has said the United States needs a "political revolution" of working-class Americans to take back control of the government from billionaires."This great nation and its government belong to all of the people and not to a handful of billionaires, their super PACs and their lobbyists," Sanders said at a rally in Vermont on May 26. Hide Caption 6 of 6

The reason behind Walker's tumble from the top of the pack in Iowa may be in those issue questions: Although 11% see him as the most electable in the field, he hasn't impressed on the issues. Walker falls below 10% on each issue tested, with his best showing the 8% who think he would best handle the economy.

When asked to name the issue that will be most important in deciding which candidate to support for president next year, Iowa Republicans likely to attend the presidential caucus most frequently cite an economic issue, with 33% naming an economy-related concern, 20% a foreign policy issue, 14% immigration, 8% social issues, and 6% government spending, taxes or the national debt. Among those who call the economy their top concern, 39% say they most trust Trump to handle it, 12% Fiorina, and 11% Walker. And those who cite a foreign policy concern also put Trump atop their list of trusted candidates for handling terrorism, but by a smaller margin: 17% trust Trump, 10% Cruz, 9% Paul.

The poll was conducted August 7-11 among a statewide sample of 2,014 Iowa adults, 544 of whom were identified as likely Republican caucusgoers based on questions about whether they are registered to vote, likelihood of voting, past voting behavior and interest in the campaign. The margin of sampling error for results among the sample of likely Republican caucus attendees is plus or minus 4 percentage points.