WASHINGTON — Mitt Romney, the frontrunner in the Republican presidential race, is in strong shape with his party's rank and file as the 2012 nomination race enters a more heated phase.

Among Republicans, 59 percent hold a favorable view of the former Massachusetts governor, according to a Bloomberg National Poll, while only 16 percent view him negatively. He's also more popular than unpopular with independent voters by a 10 percentage point margin.

While the poll shows more than half of Republicans are dissatisfied with the current choices in the field, an overwhelming 85 percent want candidates seeking their support to focus almost entirely on economic issues, not social ones.

Romney, 64, has made the economy the centerpiece of his campaign as he again pursues the White House following his unsuccessful 2008 attempt for the Republican nomination -- a race in which he focused more on social issues.

"Romney is threading the needle the way a seasoned candidate knows he must," said J. Ann Selzer, president of Des Moines, Iowa-based Selzer & Co., which conducted the June 17-20 poll. "He's saying enough of the things Republicans want to hear while holding the interest of independents."

Romney's party is not doing as well. By 47 percent to 42 percent, Americans view Republicans unfavorably. Democrats are viewed favorably by 48 percent and unfavorably by 42 percent.

Negative attitudes about the tea party are growing, with 45 percent saying they have an unflattering view of the political movement, the highest level since the poll first asked the question in March 2010. Among independents, 50 percent view the tea party unfavorably.

Among all poll participants, Romney was viewed favorably by 37 percent and unfavorably by 31 percent, with 32 percent saying they are unsure. President Barack Obama's favorable rating among the entire poll sample was 54 percent, while 42 percent viewed him unfavorably.

As the frontrunner, Romney is certain to attract increasing criticism from his Republican rivals, although he avoided such attacks during a June 13 debate in New Hampshire where the candidates kept their focus on Obama.

Romney's rivals, including former governor Tim Pawlenty of Minnesota, Rep. Michele Bachmann of Minnesota and former Utah governor and ambassador to China Jon Huntsman Jr. all have lower favorability ratings, though they aren't nearly as well known yet.

Before Romney's 2003-2007 tenure as governor in traditionally Democratic Massachusetts, he co-founded the Boston-based private-equity firm Bain Capital and helped turn the 2002 Winter Olympics in Salt Lake City, Utah, into a financial success. He is focusing on the economy and his business experience as the jobless rate for May was 9.1 percent, the highest so far this year.

"I like his stance on a lot of subjects," said poll participant Tommy Hedin, 19, who is starting college later this year and lives in Marlborough, Mass. "I think he will put the country back in a good direction if he's elected."

Others said they are only starting to pay attention to the contest and want to learn more about the Republican field.

"I don't really have a strong feeling for any of them," said poll participant Shelley Evans, 49, a retired teacher in Great Falls, Mont., who considers herself a Republican and would like to see more candidate choices for her party.

The Bloomberg poll of 1,000 adults, which has a margin of error of plus or minus 3.1 percentage points on the full sample, was conducted in the days following the New Hampshire debate. On findings involving only Republican responses, the margin of error is plus or minus 5.9 percentage points.

The Mormon faith practiced by Romney and Huntsman doesn't appear to be a major hurdle. Among potential Republican voters, 71 percent say it doesn't matter.

Huntsman's service as the Obama administration's envoy to China could prove more problematic. Among the potential Republican voters, 37 percent say such work would make a candidate a lot less attractive to them, and another 28 percent say it would make someone a little less attractive.

The poll found that actions some of the party's candidates have taken -- or proposed -- could come back to haunt them in the Republican race.

Roughly half of the survey's potential Republican voters say it would be a turnoff if a candidate backed changing Medicare to a private system with government subsidies. House Budget Committee Chairman Paul Ryan, a Wisconsin Republican, is pushing such a plan and most of the party's presidential contenders have endorsed it in principle.

Support of a health insurance mandate like the one in the federal overhaul passed by Congress last year is viewed as unattractive by two-thirds of the potential Republican voters. Romney, as governor, signed into law a Massachusetts measure that included the insurance mandate.

Three-quarters would consider a candidate who voted to raise the national debt ceiling to be less appealing.

More than half -- 58 percent -- would view support of civil unions for gay and lesbian couples as unattractive, while about half hold that view for a candidate that supports a cap- and-trade plan to cut greenhouse gases. Huntsman has supported civil unions. And during their governorships he and Pawlenty backed cap-and-trade efforts, though both have since backed away from such proposals.

Being unfaithful to a spouse makes a candidate less attractive to 83 percent of the potential Republican voters. Presidential contender Newt Gingrich, the former House speaker from Georgia, has acknowledged cheating on a previous spouse.

Gingrich, who has vowed to continue his presidential campaign amid skepticism that he can recover from resignations of his top staff members and lagging fundraising, is viewed favorably by 45 percent of Republicans. He is viewed unfavorably by 31 percent, the highest level for any declared or potential candidate tested. Among likely voters in the poll, 56 percent viewed him unfavorably.

Former Alaska Governor Sarah Palin, who has remained coy about a potential run after being the 2008 Republican vice presidential nominee, came close to Gingrich in the unfavorable ratings. She is viewed negatively by 27 percent of Republicans and 60 percent of likely voters.

Among other presidential candidates, Bachmann is viewed favorably by 43 percent of Republicans and unfavorably by 12 percent. Pawlenty, her fellow Minnesotan, is viewed favorably by 29 percent and unfavorably by 11 percent.

Republicans are still learning about Huntsman -- who formally announced his candidacy two days ago -- with 71 percent saying they don't know enough about him yet to know whether they like or dislike him. For Pawlenty and Bachmann, those numbers are 60 percent and 45 percent.

"Huntsman presents an opportunity to draw a strong response from independents," Selzer said. "His seeming liabilities will make it hard to win the nomination, potentially, but in the general election, independents could look favorably on his moderate views."