WASHINGTON — US President Barack Obama Monday took a biting preemptive strike at potential Republican 2012 rivals, damning one with faint praise and warning others not to get too comfortable at the White House.

Obama, who has already taken preliminary steps towards setting up his 2012 reelection campaign, entertained American state governors at the White House -- including several possible pretenders to his job.

The president aimed a good natured slap at Mississippi Governor Haley Barbour, Indiana Governor Mitch Daniels, and perhaps long-shot Republican possibility Chris Christie from New Jersey.

"I hope, today, all of you feel free to make yourselves at home. For those of you with a particular interest in the next election, I don't mean that literally," Obama said at a White House meeting.

The president also sought to score an early debating point against a man who was not in the room, former Massachusetts governor and failed 2008 Republican candidate Mitt Romney, who is considering another tilt at the White House.

One of Romney's key policies as governor was the framing of a universal health care plan which foreshadowed some aspects of Obama's key bill reforming countrywide US health insurance.

The plan could be a political liability for Romney in the Republican race, in which candidates must appeal to the most fervent conservative sectors of opinion which despise any government role in the private medical system.

"I agree with Mitt Romney, who recently said he is proud of what he accomplished on health care," Obama said, in a soundbite likely to be recycled over and over by the Republican's rivals for the 2012 nomination.

Obama appeared to be referring to a quote in which a Romney spokesman said the former governor was proud of getting everyone in Massachusetts health care insurance coverage.

But the spokesman also drew a distinction between Romney's approach and Obama's plan to rein in insurance abuses and require everyone to buy coverage from the federal level.

It was not the first time that Obama had appeared to relish making a potential 2012 rival squirm.

In January, during a visit by Chinese President Hu Jintao, Obama was asked about the presidential prospects of his ambassador to Beijing Jon Huntsman, a Republican.

He said Huntsman had done an "outstanding job" as ambassador to China and shown enormous skill, dedication and talent.

"I'm sure he will be very successful in whatever endeavors he chooses in the future, and I'm sure that him having worked so well with me will be a great asset in any Republican primary," Obama added.

Huntsman, a former Utah governor, has since resigned, and has given every indication of considering a campaign for the Republican nomination.