SCOTTSDALE, Arizona (Reuters) - Presumptive Republican presidential nominee Mitt Romney worked on Friday to rally party leaders behind his cause and overcome lingering suspicions that he is too moderate, but failed to get all to pledge allegiance.
Romney called for unity at a Republican National Committee conference in the Arizona desert that brought together party representatives from each state, some of whom had backed one of Romney's rivals for the nomination.
In his speech, Romney kept the focus on Democratic President Barack Obama's handling of the sluggish U.S. economy. He recognized his vanquished Republican rivals, from Michele Bachmann to Rick Santorum, mentioning them all by name and thanking them for having the courage to run.
"Each one of them is going to play a vital role in making sure we win in November," said Romney. The former Massachusetts governor needs as much support as he can get from fellow Republicans in what is expected to be a tough fight with Obama.
Romney lagged Obama by six percentage points in a new NBC/Wall Street Journal survey, although a few other polls have shown him ahead.
Some Republican committee members declined to fall in line with Romney's attempts on Friday to bring the party together under his candidacy after months of bruising primary fights.
In a private reception before his luncheon speech, Republican delegates were asked to sign a pledge to support Romney and about 100 did so, a campaign official said.
But Iowa's three conservative representatives did not sign the pledge and CNN said there was a heated exchange in the hallway outside the reception.
Some party representatives had been hoping one of Romney's rivals would have become the standard bearer. Iowa, for example, narrowly voted for Santorum over Romney in its January nominating contest.
Reinforcing the idea that Romney, who is trying to dispel criticism that he is too stiff, has a "likeability gap" with voters, a recent Washington Post/ABC News poll offered a glaring picture: 56 percent said they had a favorable opinion of Obama while only 35 percent said the same of Romney.
The NBC/Wall Street Journal poll also showed that the president is seen as more likeable and someone who cares more than Romney, a former business executive, about average people. Romney had 43 percent to Obama's 49 percent in a match-up.
But in a key area - ideas to improve the U.S. economy - Romney led Obama by 40-34 percent.
'COMING ON BOARD'
On his second presidential bid, Romney is playing well to the Republican establishment. More state chairmen are now getting behind him after the departure from the race last week of Santorum, who was his main rival.
"My sense is that when the primary process started, a lot of state chairs liked a lot of the different candidates, but now that Romney is almost the presumptive nominee, they're all coming on board," said Steve Duprey, a party leader in New Hampshire. "He's proven himself after a long, rugged battle and I think people are starting to get enthusiastic."
The party's presidential nominee from 2008, U.S. Senator John McCain of Arizona, conducted a symbolic passing of the torch at Friday's event.
"I am so gratified to see our party coming together on a solid team that is going to elect him president of the United States," McCain said at the lunch.
Duprey said Romney should use his wife, Ann, as often as possible on the campaign trail to lighten up his image.
"The more time he spends out on the campaign trail with Ann Romney, who is his best surrogate, and the more time he spends in smaller, more intimate events ... the more people will see he's a competent and genuine person," he said.
Romney also moved on Friday to try to improve his standing among Hispanic voters, staging a roundtable to discuss issues important to them. Hispanics could be a key voting bloc in Southwestern states like Arizona, New Mexico and Nevada.
Latinos traditionally support Democratic candidates by an overwhelming majority. Republicans, however, believe they can draw Hispanic voters from Obama by pressing Romney's economic message, including the case that the growing minority group has as big a need for jobs as anyone else.
RNC Chairman Reince Priebus said the main issue for Hispanics was jobs, not immigration, which he said in any event Obama has failed to address in three years as president.
"He didn't deliver a darned thing on immigration reform," Priebus told Reuters.
(Editing by Steve Holland and Paul Simao)