(CNN) - Mitt Romney on Monday advanced his criticism of Republican Rep. Todd Akin, saying he could not defend the Senate candidate over his controversial remarks about rape and pregnancy.
In an interview with New Hampshire television station WMUR, Romney said Akin "should spend 24 hours considering what will best help the country at this critical time," according to a tweet by the station's political director Josh McElveen.
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"I can't defend what he said, I can't defend him," Romney also said, according McElveen's Twitter feed.
His comment comes after a major Republican campaign group–the National Republican Senatorial Committee–signaled it would pull funding from Akin's Senate bid in Missouri against incumbent Democratic Sen. Claire McCaskill. The group's chairman, Sen. John Cornyn of Texas, suggested in a statement that Akin "carefully consider what is best" in terms of his next step.
In an interview with the National Review Online published earlier Monday, Romney said that Akin's "comments on rape are insulting, inexcusable, and, frankly, wrong."
"Like millions of other Americans, we found them to be offensive," Romney said, adding: "I have an entirely different view. What he said is entirely without merit and he should correct it."
Later Monday, the same news outlet-National Review Online-called on the congressman to resign from his position as Senate nominee in an editorial titled, "Step Aside, Todd Akin,"
Adding to the drumbeat of intra-party criticism, some Republicans in Tampa, ahead of next week's Republican National Convention, expressed their frustration about Akin's comments.
A Republican National Committee member from a critical swing state predicted that a likely win in the Missouri Senate contest was now in jeopardy. As for the presidential campaign, the RNC member noted that Akin's remarks have caused an unnecessary distraction for Mitt Romney's presidential campaign.
"It is a terrible distraction in a Senate race that we were poised to win," said the RNC member, who spoke candidly on the condition of anonymity. "Akin needs to do the right thing and quietly leave the ballot.
"It has also changed the national conversation back to this supposed Republican faux war on women. That is not where Gov. Romney and his ticket want to spend their time on between now and November 6."
A senior Republican with strong ties to Missouri said Republicans are concerned that Akin will not be allowed to be removed from the ballot even if he succumbs to pressure and asks to be removed from the ballot.
"What was he thinking," said the Republican, who noted that regardless of what happens the GOP will now be sending a weakened Senate candidate into the November election.
On the other hand, top officials from the conservative group Family Research Council came to Akin's defense on Monday.
Connie Mackey, who heads the group's political action committee, said the group "strongly supports" Todd Akin.
"We feel this is a case of gotcha politics," Mackey told reporters in Tampa, where the Republican National Committee was gathering ahead of the party's convention next week. "He has been elected five times in that community in Missouri. They know who Todd Akin is. We know who Todd Akin is. We've worked with him up on the hill. He's a defender of life."
On Sunday, Akin said in a local TV interview that "legitimate rape" rarely resulted in pregnancy.
"First of all, from what I understand from doctors, that's really rare," Akin said of rape-induced pregnancy in an interview with KTVI. A clip of the interview was posted online by the liberal super PAC American Bridge.
"If it's a legitimate rape, the female body has ways to try to shut that whole thing down," he added.
Following a resulting firestorm over his comments–from Republicans and Democrats alike–Akin apologized Monday afternoon during an interview on Mike Huckabee's radio show.
"I made that statement in error. Let me be clear. Rape is never legitimate. It's an evil act, and it's committed by violent predators," he said. "I used the wrong words in the wrong way. What I said was ill conceived and it was wrong. For that I apologize."
However, the Missouri Republican said he would not be backing down in his fight for the Senate seat.
"I don't know that I'm the only person in public office who suffered from foot in mouth disease here," the congressman said. "On the other hand there are so many good people in Missouri who nominated me."
Akin said he's focused on the economy and feels "just as strongly as ever" that his background would be a "big asset" in replacing McCaskill.
"I'm not a quitter. My belief is we're going to take this thing forward, and by the grace of God we're going to...win this race," he said.
Hours after the interview, Akin stood by his pledge to stay in the contest.
"I am in this race to win. We need a conservative Senate," Akin posted on Twitter, urging supporters to donate to his campaign.
His spokesman, Ryan Hite, further reiterated Akin's vow to continue his campaign.
"Akin is not dropping out of this race," Hite told CNN.
– CNN's Mark Preston, Peter Hamby, Chris Welch, Ashley Killough and Kevin Liptak contributed to this report.