Republican Rep. Todd Akin on Tuesday defied top GOP officials who were demanding that he abandon his run for the U.S. Senate in Missouri after claiming that women who were victims of "legitimate rape" couldn't get pregnant.

Akin refused to quit the race by a Tuesday deadline that would have allowed the party to replace him on the Nov. 6 ballot, ignoring a barrage of pleas and threats from his Missouri Republican elders, Republican presidential contender Mitt Romney and others, who fear Akin may derail the party's chances of taking over the Senate next year.

Before his comment ignited a national political fight over the issue of abortion Sunday, Akin had enjoyed a slight lead over Democratic incumbent Sen. Claire McCaskill, who Republicans considered one of the most vulnerable of the 23 Democratic senators up for re-election this fall. Akin apologized for his remarks, but Republicans, who need to pick up just four seats to secure a Senate majority, have all but abandoned him and hopes for reclaiming the Missouri seat.

"It would take a miracle," for Akin to win, Jennifer Duffy, a senior editor for the Cook Political Report, told The Washington Examiner.

Duffy, who analyzes Senate races for Cook, said Akin will be financially crippled now that the party's fundraising arm and supporting super-PACs have withdrawn their support for him, leaving him at a serious disadvantage more than two months from Election Day.

"Meanwhile, McCaskill can run a very positive campaign, virtually unanswered by Akin," Duffy said. "And if she chooses to run a negative campaign, she has a lot of fodder now."

Missouri's former Republican senators and governors on Tuesday joined the call for Akin to quit. Romney, too, issued a statement saying that Akin "should accept their counsel and exit the Senate race."

Vice presidential candidate Paul Ryan, a colleague of Akin's in the House, phoned the Missouri Republican earlier in the day with the same message: Get out.

But Akin told conservative commentator Sean Hannity that Romney had "bid this thing up and made a bigger deal about it than he needed to."

Akin, who has bucked party leaders in the past, said his decision to remain in "is a question of principle."

But for others in the GOP, it has become a question of timing.

Since Akin missed Tuesday's deadline to remove his name from the ballot, a court order would have to be issued by Sept. 25 to remove him. Republicans continue to look for potential replacements, including Rep. Jo Ann Emerson, who represents southeastern Missouri, and former Missouri House Speaker Catherine Hanaway.

Missouri political analysts, meanwhile, insist Akin can still win. The state's electorate leans Republican, and there are very few undecided independent voters, they noted.

"At the end of the day, no Republican voter is going to not vote for Akin and switch to Claire McCaskill because of these comments," Missouri State University political science professor George Connor said.