Newt Gingrich officially ended his campaign on Wednesday, and President Barack Obama's re-election campaign released a web video of clips from the Republican primaries in which the former House speaker sharply criticized Mitt Romney —Obama's likely opponent in November.

Facing a tight race, Obama's campaign put forward Gingrich's anti-Romney messages on issues from immigration to the presumptive nominee's tenure as a venture capitalist.

Gingrich led the Republicans out of 40 years of minority status in the lower house of Congress in 1994 but later resigned under an ethics cloud. He tried to stage a political comeback in this year's presidential contest, but he won primaries in only conservative South Carolina and Georgia, the state he represented for 20 years.

As he officially ended his campaign in an appearance in Arlington, Va., Gingrich thanked a long list of supporters and said the run for the Republican nomination had been "an amazing year" for him and his wife, Callista.

"Suspending the campaign does not mean suspending citizenship," said Gingrich as he read off a valedictory enumerating his long history of working for what he saw as critical issues for the United States and conservative political victories.

'This is a choice between Mitt Romney and the most radical, leftist president in American history.'—Newt Gingrich

Looking forward to the November election, Gingrich put himself behind Romney's candidacy by saying there was no choice between him and Obama. But there was little praise for Romney's candidacy, a reflection of lingering hard feelings after the presumptive nominee crushed him and closest Republican rival Rick Santorum with scorching negative advertisements in the primaries.

"As to the presidency, I'm asked sometimes is Mitt Romney conservative enough? And my answer is simple: compared to Barack Obama? This is not a choice between Mitt Romney and Ronald Reagan, this is a choice between Mitt Romney and the most radical, leftist president in American history."

Bitter primary battle

The bitter primary battle gave the Obama camp plenty of material for the video of a fellow Republican lashing out at Romney.

Romney, meanwhile, was kicked off his campaign in Virginia, a critical swing state that is not firmly behind either the former Massachusetts governor or Obama, who carried it in 2008. Republican George W. Bush won the state in 2000 and 2004.

At a rally in the Northern Virginia suburbs of Washington, Romney spoke about the economy.

Romney slams banking regulations 

After several days of campaigning marked by the anniversary of the death of Osama bin Laden, Republican presidential frontrunner Mitt Romney's campaign returned to familiar themes of the economy and jobs. He painted small businesses as heroes of the economy and said legislation Obama signed to regulate the banking industry was hurting smaller institutions.

"They've gotten bigger; and the small community banks are the ones that have been most hurt," Romney said.

"What I would do? People ask me, 'What would you to get the economy going'? and I say, 'well look at what the president's done, and do the opposite,"' Romney told a group gathered at a warehouse in Northern Virginia. 

Romney was in the Washington area to raise money and hold a series of meetings at the Republican National Committee, where he's working to integrate his campaign with the national party apparatus.

Ann Romney introduced her husband with an appeal to the women in the audience.

"We appreciate all these women being here," she said, noting that Exhibit Edge, the company where the event was held, is run by a woman. "We know what women can do … how women actually do make the world go round."