A month after abruptly dropping out of the presidential race, former Gov. Tim Pawlenty re-emerged Monday as the new national co-chairman for Mitt Romney's presidential campaign.

Despite their earlier differences over health care and the debt ceiling, Pawlenty offered a hearty endorsement of Romney and will become a chief surrogate for the former Massachusetts governor.

"Romney is running for president because he is deeply committed to our country, troubled by its current condition, and I believe he can turn it around," Pawlenty said. Romney said Pawlenty will be a "trusted adviser."

The Democratic National Committee on Monday wasted no time reminding reporters that Pawlenty had spent months bashing Romney and his proposals, even dubbing his health plan, "Obamneycare."

Pawlenty chose Romney not only over the current front-runner, Texas Gov. Rick Perry, but over fellow Minnesotan Michele Bachmann, whose August entry into the race accelerated Pawlenty's departure.

Since his disappointing third-place showing in an Iowa straw poll in mid-August, Pawlenty has kept a low profile, popping up only last week in select television appearances.

Pawlenty's new role will keep him in the national conversation and give him a platform from which to travel to the early-voting states.

"It keeps him as a player and it will probably make it more likely that people will look at him as maybe a potential running mate," said Andy Brehm, a Republican attorney from Minnesota. Brehm was a Pawlenty supporter who recently switched to Romney.

Pawlenty said on Monday, as he has several times before, that he has no interest in being a running mate. Pawlenty, who served as a surrogate for 2008 GOP nominee John McCain, was nearly chosen by McCain but ultimately passed over in favor of Sarah Palin.

Some Republicans speculated that Pawlenty's endorsement could ensure Romney's help in retiring whatever campaign debt Pawlenty has left. The former Minnesota governor left the campaign having already cut back on some expenses and with donors drying up.

But, a source told the Star Tribune, Pawlenty would not have endorsed Romney for that reason. "Whatever debt was outstanding could have been managed with or without the benefit of the endorsement," the source said.

Pawlenty's endorsement gave the Romney campaign a morning bump in the national media, but that quickly dissipated.

By mid-afternoon, Perry stole back the spotlight -- as he has done repeatedly since his August entry into the nomination race -- with the news that he had been endorsed by Louisiana Gov. Bobby Jindal.

Neither endorsement may do much to sway activists in early-voting states.

Eric Rosenthal, of Cedar Rapids, Iowa, was on Pawlenty's Iowa team, but promptly switched to Perry after the Minnesota governor dropped out. Pawlenty's endorsement of Romney will not change that.

"I think Iowans just make up their own minds," Rosenthal said. "We're just fiercely independent. ... They are not going to be told by anybody about what they want."

Rachel E. Stassen-Berger • Twitter: @rachelsb