WASHINGTON - At a time when his campaign is working to attract reluctant conservatives, Mitt Romney won the backing Thursday of onetime rival Michele Bachmann, who has vowed to use her connections in evangelical and tea party groups to help unite the party behind him.

"This is what victory looks like," Rep. Bachmann of Minnesota declared Thursday in Portsmouth, Va., as she took the stage with the presumptive Republican nominee and Virginia Gov. Bob McDonnell nearly four months after she dropped her own bid for the White House.

"When you look at 30-plus months of unemployment above 8 percent; when you look at doubling of America's energy prices at the pump, when you look at debt accumulation in excess of $5 trillion under his watch, there is no question in my mind that Americans will go to the polls and they'll be saying 'Mr. President, you're fired,' " Bachmann said to applause. "Instead, we will soundly stand for someone who believes in America, who believes in our children, who believes in the hope of opportunities for this next generation."

Bachmann made no mention of her biggest criticism of Romney while she was running against him: that his health-care plan in Massachusetts was a precursor to Obama's federal health-care law.

In a statement, she called Romney "the only option" in the presidential race and called on "conservatives, independents, and disaffected Democrats" to join her in denying Obama a second term.

Bachmann's warmth and graciousness toward Romney stood in contrast to the comments of former House Speaker Newt Gingrich, who formally withdrew from the race on Wednesday.

Gingrich offered only faint praise for Romney: that he was more conservative than the current occupant of the White House.