By Steve Holland and Thomas Ferraro
WASHINGTON (Reuters) - Mitt Romney, sensing the Republican presidential nomination will be his, is working behind the scenes to try to unify conservatives behind him and he may be gaining some traction.
Romney's objective is to ease conservative doubts about his candidacy raised repeatedly by chief rivals Rick Santorum and Newt Gingrich, who denounce him as a Massachusetts moderate who will forsake conservative views if he becomes the nominee.
Romney privately made the rounds on Capitol Hill on Thursday, meeting a leading conservative senator who has not endorsed him, Jim DeMint of South Carolina, and holding a fund-raiser at a Washington hotel attended by several senators and members of the U.S. House of Representatives.
Romney sat down as well with Paul Ryan, the conservative chairman of the House Budget Committee.
DeMint, a member of the Senate Tea Party Caucus who had endorsed Romney's failed 2008 presidential bid, made clear in remarks to reporters that he has no immediate plans to endorse this year, but he spoke warmly about Romney.
"I can tell conservatives from my perspective ... I'm not only comfortable with Romney, I'm excited about the possibility of him possibly being our nominee. His leadership skills, the fact that he hasn't lived his life in Washington, there's a lot to like there," DeMint said.
In addition, a top Romney supporter in the Senate, John McCain of Arizona, took the opportunity of a weekly lunch with his Republican colleagues on Wednesday to urge them to rally behind Romney.
McCain, the party's 2008 presidential nominee, said that every day that goes by with Republicans squabbling over who their nominee will be makes it that much more difficult to defeat Democratic President Barack Obama in the November 6 election, a person familiar with McCain's remarks said.
HARD FOR SANTORUM, GINGRICH
Romney's convincing win at the Illinois primary on Tuesday was a major boost to his candidacy and has left chief rival Santorum with dwindling options to overtake him. Also significant was the endorsement by former Florida Governor Jeb Bush.
"It looks like it's going to be very hard for Santorum and Gingrich to keep him from winning the number of delegates necessary for the nomination," said Republican strategist Ron Bonjean. "Therefore, it's likely you'll see more high-profile Republicans coming out in support of his candidacy."
Many conservatives have suspicions about Romney on social issues given his past support of women's right to choose whether to have an abortion, a position he has since renounced. The healthcare plan he developed for Massachusetts, which was used by Obama for the U.S. overhaul that conservatives want to repeal, is also a problem.
But the Romney campaign hopes to sway them in part by pressing his commitment to fiscal issues near and dear to conservative hearts -- lower taxes, less government regulation and less debt.
During his morning Capitol Hill fund-raiser, Romney spoke about what he called Obama's "assault on economic freedom" and the need to create conditions for businesses to generate job growth and take steps to reduce soaring U.S. deficits.
Romney raises his fiscal conservative credentials at every opportunity, including at a campaign event on Wednesday in Arbutus, Maryland.
"I want to get our economy going again and I know how to do it," he said there. "It's by restoring the principles that made us the nation that we are."
But a comment by a top Romney campaign adviser, Eric Fehrnstrom, has provided ammunition for Santorum and Gingrich.
Fehrnstrom told CNN that during a general election campaign Romney would reset his campaign much like shaking an Etch A Sketch toy. Santorum and Gingrich insisted this is evidence that if Romney wins the nomination, he will forsake conservative causes and return to his moderate roots, a scenario he has rejected.
While Romney is working to consolidate support behind him, his aides recognize the race is not yet won and foresee more weeks of battles. Santorum looks on track to win Louisiana on Saturday, meaning the two rivals will face a potentially pivotal contest in Wisconsin on April 3.
On April 24, the map favors Romney as several northeastern states vote.
"We're going to have to grind it out through April ... and see if Santorum wants to take a second look," said a Romney adviser.
Republican strategist Tucker Eskew said there was no point in Romney's campaign calling on Santorum to pull out of the race.
"I think the Romney campaign would be wise to tend to their own momentum and what they can control and leave it to other candidates to do what's right out of self-interest, the party's interest and the national interest," he said.
(Additional reporting by Donna Smith; Editing by David Brunnstrom)