WASHINGTON -- At a time when his campaign is working to attract reluctant conservatives, Mitt Romney won the backing Thursday of one-time 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 chief 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 and offered only faint praise for Romney: that he was more conservative than the current occupant of the White House.

During an interview with CNN's Wolf Blitzer on Thursday afternoon, Gingrich insisted that he was committed to helping elect Romney and said he had met with his campaign manager, as well as other policy advisers, to schedule a joint appearance soon.

"Look, I said I'm going to campaign for him," Gingrich told Blitzer. "I said he will appoint dramatically better judges than the president. He'll do a dramatically better job creating jobs than the president. He'll do far more to balance the budget than the president."

"I went down a pretty long list of why I think Mitt Romney is better than Barack Obama," he continued. "This is a comparative business. And our choice isn't Mitt Romney or Ronald Reagan."

But Gingrich, whose campaign collapsed after he faced millions of dollars of negative ads from Romney and his allies, clearly wasn't quite ready to forgive and forget. Blitzer pressed him on whether he stood by his earlier comments that the former Massachusetts governor was "a liar."

"The governor said things, at times, that weren't true," Gingrich said. "I think that's true." But he added: "I also believe that compared to Barack Obama, I would trust Mitt Romney 100 times over."