Newt Gingrich formally ended his bid for the Republican presidential nomination today and announced plans to endorse former rival Mitt Romney.
Gingrich was at one brief point a frontrunner in the race, winning primaries in Georgia and South Carolina.
The former speaker of the House said he wished he would have focused on more extract ideas, such as brain research and energy independence. With "more discipline and more courage to be more outside the mainstream, it might have worked better," he said.
His campaign also struggled to raise money, and he is leaving the race with more than $4 million in debt. Gingrich has said he will back Romney's candidacy and that in return the presumed GOP nominee will help him collect funds to cover his debt.
"Mitt Romney met the first criteria of being a good candidate: He won," Gingrich said. "Now, you have to respect that." He added: "We sure didn't give it to him. We did everything we could to slug it out with him, and he ended up being tough enough and being good enough at raising money" to prevail.
Romney's former rival Rick Santorum has yet to offer his endorsement. The two men will reportedly meet Friday, so the former Pennsylvania senator can assess how conservative issues will be addressed by the Romney campaign.
Ron Paul, who has not won any primaries, is still technically in the race. However, he only has 80 delegates to Romney's 847.