Former Massachusetts governor Mitt Romney, widely regarded as the front-runner in the Republican presidential race, has decided not to participate in this year’s Iowa Straw Poll or any other such tests before the 2012 primaries and caucuses, his campaign announced Thursday night.

By skipping the Aug. 13 straw poll, an important stop in the nominating contest, Romney offered the clearest signal yet that he may not compete vigorously in Iowa, home to the first-in-the-nation caucuses and where social conservatives are traditionally influential.

“Our campaign has made the decision to not participate in any straw polls, whether it’s in Florida, Iowa, Michigan or someplace else,” Romney campaign manager Matt Rhoades said in a statement. “We respect the straw poll process. In the last presidential campaign, we were both strengthened as an organization and learned some important lessons by participating in them. This time we will focus our energies and resources on winning primaries and caucuses.”

Romney won the Ames straw poll in 2007. But he ended up losing the more-important Iowa caucuses, where delegates to the Republican National Convention were decided, to Mike Huckabee, the runner-up in the straw poll.

The straw poll in Ames, held by the state’s Republican Party, can be a costly effort for campaigns — four years ago, Romney spent millions of dollars and months of effort on the event — and a poor performance there this time could have diminished his standing in the Republican field.

Romney still plans to compete in the caucuses in February, and his advisers said he will return to Iowa for future campaign events.

“The campaign is making a smart decision not to compete in the upcoming series of straw polls,” Brian Kennedy, a Romney adviser and former Iowa state GOP chairman, said in a statement. “Mitt’s focus is on winning the nomination, not the straw polls. Mitt will be back in Iowa this summer and will participate in the Ames debate,” scheduled two days before the straw poll.

The decision, first reported Thursday night by the Wall Street Journal, could recast the race in Iowa. It presents an opportunity for former Minnesota governor Tim Pawlenty, who has made Iowa central to his overall strategy, and Rep. Michele Bachmann (Minn.) and other announced and potential candidates who appeal to Evangelical voters.

“I joined Governor Pawlenty’s campaign because I knew he could put his record before voters everywhere,” Matt Whitaker, chairman of Pawlenty’s Iowa steering committee, said in a statement. “The Ames straw poll is a great gathering of conservatives, and Governor Pawlenty’s solid record will be well received there. I look forward to joining thousands of Iowans in casting my vote for Governor Pawlenty in Ames this summer and in the caucuses this winter.”