JEFFERSON CITY, Missouri (AP) ― Republican presidential candidate Mitt Romney called on a Republican congressman to abandon his U.S. Senate bid in the Midwest state of Missouri after his comments about rape undermined the party’s bid to gain control of Congress of in November.

Rep. Todd Akin did not heed Romney’s call however, as he continued to defy top Republicans on Tuesday to forge ahead with his besieged Senate campaign. Akin declared that his party’s leaders were overreacting by abandoning him because of comments that women’s bodies can prevent pregnancies in cases of “legitimate rape.”

Akin was once seen as a strong challenger to incumbent Democrat Claire McCaskill in Missouri, a pivotal target for Republicans as they attempt to win control of the Senate. Republicans already control the House of Representatives.

Akin’s bid now faces tall obstacles: a lack of money, a lack of party support and no assurance that his apologies would be enough to heal a self-inflicted political wound. But Akin refused to back down, ignoring a key deadline Tuesday to withdraw from the ballot.

“I misspoke one word in one sentence on one day, and all of a sudden, overnight, everybody decides, ‘Well, Akin can’t possibly win,’” he said on a national radio show hosted by former Republican presidential candidate Mike Huckabee. “Well, I don’t agree with that.”

Akin predicted he would bounce back from the political crisis threatening his campaign.

“I’m in this race for the long haul, and we’re going to win it,” he told radio host Dana Loesch in St. Louis.

If he stays on the ballot, Akin will have to rebuild without money from the national party and with new misgivings among rank-and-file Republican voters who just two weeks ago propelled him to a comfortable victory in a hotly contested three-way primary.

At several points during the interview with Huckabee, Akin focused on the idea he had misplaced a single word during a Sunday interview with St. Louis television station KTVI. But Akin has been roundly criticized both for using the phrase “legitimate rape” and saying a woman’s body has the ability to prevent conception after such an attack.

Hours earlier, Akin posted an online video in which he apologized again for his remarks. Campaign spokesman Ryan Hite said the apology was intended to cover both the reference to “legitimate rape” and Akin’s assertion that rape victims have a natural defense against pregnancy.

As Republicans pull their financial support, it’s not clear if the increasingly isolated Akin will be able to wage a prolonged advertising battle against McCaskill.

In a potential sign of his strategy, Akin appealed Tuesday to Christian evangelicals, anti-abortion activists and anti-establishment Republicans. He said he remains the best messenger to highlight respect for life and liberty that he contends are crumbling under the big-government policies of President Barack Obama.

Republican leaders, however, intensified their pressure on Akin to exit.

Sen. Roy Blunt issued a joint statement Tuesday with all of Missouri’s former Republican senators ― John Ashcroft, Kit Bond, Jim Talent and John Danforth ― saying “it serves the national interest” for Akin to step aside.

Pointing to the group, Romney said the congressman should “accept their counsel.”

A Romney aide said the candidate had been inclined to let Akin make the decision on his own. But after the Missouri lawmakers called for Akin to go, Romney wanted to make his position clear, said the aide, who requested anonymity because the aide was not authorized to publicly discuss Romney’s thinking.

Akin provoked a political uproar when he was asked in the KTVI interview whether his general opposition to abortion extends to women who have been raped.

“It seems to me, first of all, from what I understand from doctors, that’s really rare. If it’s a legitimate rape, the female body has ways to try to shut that whole thing down,” Akin said.

While repeating his apology, Akin began taking a more aggressive tone Tuesday.

Asked by Huckabee if Akin felt betrayed by fellow Republicans, Akin replied: “I hadn’t done anything morally or ethically wrong, as sometimes people in politics do ... It does seem like a little bit of an overreaction.”

To continue his campaign, Akin will need the support of social conservatives, who have formed his political base through a 12-year congressional career.

Some have rallied to his side. Akin’s campaign released an open letter Tuesday from Jack Willke, former president of the U.S. National Right to Life Committee, stating he was “outraged at how quickly Republican leaders have deserted” Akin.

Akin “remains a strong and courageous pro-life leader ― and awkward wording in one sound bite doesn’t negate that,” Willke’s statement said.

If Akin were to leave, state law gives the Republican state committee two weeks to name a replacement. Akin can withdraw from the race as late as Sept. 25, but after Tuesday, he would need a court order to do so.