Ending a yearlong campaign and a weeklong farewell, former House speaker Newt Gingrich formally ended his presidential candidacy Wednesday in Arlington, Va.

Repeating an earlier pledge, Gingrich said he would help presumptive Republican nominee Mitt Romney try to defeat President Obama.

“I’m asked sometimes, ‘Is Mitt Romney conservative enough?’ and my answer is simple,” Gingrich said. “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.”

Advertisement - Continue Reading Below

The Obama campaign earlier in the day released a video showing some of Gingrich’s most pointed criticisms of Romney.

Gingrich devoted much of his exit speech to thanking his supporters, whom he addressed Tuesday in a video previewing the official suspension of his campaign. A campaign spokesman announced last Wednesday that Gingrich would drop out this week.

Gingrich thanked former GOP presidential candidates Rick Perry and Herman Cain, who endorsed Gingrich after making their own departures from the race. He also tipped his hat to billionaire casino mogul Sheldon Adelson, “who single-handedly came pretty close to matching Romney’s super PAC.”

Adelson, along with his wife Miriam, donated $20 million to Winning Our Future, a super PAC that supported Gingrich’s candidacy.

Gingrich recalled the high points of his campaign, including a primary victory in his home state of Georgia, where, he noted, 156 of 159 counties backed him.

“It was nice to feel that we had a very strong base of support from the people who know us best,” he said.

Gingrich also praised the voters of South Carolina, where he earned his only other win.

Gingrich collected a total of 137 delegates during the primary season, third among Republican candidates. Former Pennsylvania Senator Rick Santorum had 259 when he bowed out last month; Romney has 847 and needs only 197 more to officially secure the party’s nomination.

Federal Election Commission filings showed that Gingrich’s campaign was $4.3 million in debt at the end of March.

Gingrich poked fun at himself during Wednesday’s speech, saying his wife, Callista, had pointed out to him “approximately 219 times — give or take three — that the moon colony was probably not my most clever comment in this campaign.”

“I thought, frankly, in my role of providing material for ‘Saturday Night Live’ it was helpful,” Gingrich said.

But he added that he is serious about beefing up space exploration, which is on the wane.

“If we’re going to be the leading country in the world, we need to be the leading country in space,” Gingrich said.

Gingrich also spoke out against what he termed “radical Islam” and, in keeping with his promise to continue campaigning against the president, suggested the Obama administration is out of touch with the current state of Al Qaeda.

“It was nice that the president broadcast from Afghanistan,” he said, referring to the president’s surprise visit to Kabul Tuesday. “The center of Al Qaeda today is Yemen. I’m not sure the White House has gotten that briefing yet, but they will eventually.”