Washington (CNN) -- GOP presidential candidate Mitt Romney won the close-watched Conservative Political Action Conference presidential straw poll on Saturday.
Romney, the former governor of Massachusetts, took 38% of the vote in the poll. Former Pennsylvania Sen. Rick Santorum received 31%, former House Speaker Newt Gingrich was at 15% and Texas Rep. Ron Paul stood at 12%.
When asked about their preference for vice president, 34% of the attendees at the conservative conference chose Florida Sen. Marco Rubio.
Romney's win took some of the sting out of a bad week for the former governor, who saw the momentum he had gained with back-to-back wins in Florida and Nevada slowed by going 0-for-3 on Tuesday in contests in Colorado, Minnesota and Missouri.
Conservatives have had lingering doubts about the depth of Romney's conservative convictions, which has kept him from being able to run away with the nomination.
"Honored to have won the CPAC straw poll," Romney tweeted after the results were announced. "I'm heartened that so many friends here agree with me about the need for conservative change."
In an address to the conference on Friday, Romney tried to convince the conservative leaders and activists gathered that he was one of them, describing himself as a "severely conservative" governor of Massachusetts who stood with conservatives in the fight against same-sex marriage and abortion.
He framed his conservatism with his stable family and his private sector experience and defended his business record -- for which Gingrich and Santorum have attacked him. Those attacks have made some Republicans uncomfortable.
"I started new businesses and turned around broken ones, and I am not ashamed to say that I was very successful at it," he said. "I know conservatism because I have lived conservatism."
He took broad swipes at President Obama and a single, subtler one at his two closest challengers, Santorum and Gingrich, portraying himself as a Washington outsider compared to Gingrich, the former House speaker who resigned his post, and Santorum, whom Romney has hammered over his record on earmarks during his time in Washington.
"I am the only candidate in this race, Republican or Democrat, who has never worked a day in Washington," he said. "I don't have old scores to settle or decades of cloakroom deals to defend."
Winning the straw poll would have capped a stunning turnaround for Santorum with his earlier three-state sweep. His campaign reported that it had raised $1 million a day in the three days following his sweep.
Santorum used most of his address Friday to attack Obama but also took an opportunity to tie the front-runner to the president, calling Romney's health care program in Massachusetts the "stepchild" of Obama's sweeping health care reform.
But the straw poll also gives Santorum an argument that he is the stronger conservative challenger to Romney than Gingrich.
Gingrich had surged to challenge Romney near the end of last year and stunned him by winning South Carolina's primary, which has been won by every one of the party's eventual presidential nominees since 1980.
But Romney successfully counter-punched, with his campaign and super PACs that support his candidacy pouring millions of dollars into attack ads that blunted Gingrich's growing momentum.
Gingrich used his CPAC speech to portray himself as the heir to Barry Goldwater's and Ronald Reagan's conservative movement, slamming a GOP establishment that lacks the "toughness," "commitment," and "philosophy" necessary to build a political majority.
"This is the year to reset the country in a decisive, bold way," Gingrich declared. "This is going to be a big choice, big decision election."
Paul, the fourth major Republican candidate, was invited but opted to stay on the campaign trail in Maine, which announces the results of its caucuses later Saturday.
CNN's Peter Hamby, John Helton, Ashley Killough, Kevin Liptak and Alan Silverleib contributed to this report