UPDATE: (CNN) -- Despite five past and present Republican senators from Missouri calling for Rep. Todd Akin to withdraw from the campaign following controversial remarks he made about rape, he says he plans to continue his Missouri Senate bid.
Republican Senate candidate Todd Akin, under fire for his controversial comments about rape, faces a Tuesday deadline to withdraw from the U.S. Senate race in Missouri as some in his party are urging.
Akin, a six-term congressman, caused an uproar among both Republicans and Democrats after he said in a television interview Sunday that a woman's body is capable of preventing pregnancy in cases of "legitimate rape."
Top congressional Republicans, including House Speaker John Boehner, Senate GOP leader Mitch McConnell and Sen. John Cornyn of Texas advised Akin to spend time considering what is best for his family, party and country -- political code for urging him to withdraw.
Republican National Committee chairman Reince Priebus called on Akin to exit the race, even urging the congressman to stay away from the GOP convention.
"I would prefer that Todd Akin do the right thing for our party and our candidates, and I would prefer him not come," Priebus said on CNN's "Erin Burnett OutFront."
Missouri election rules allow a candidate to withdraw with little difficulty through Tuesday at 6 p.m. ET, which is 11 weeks prior to the November 6 election.
After Tuesday, the candidate must get a court order and pay for any necessary reprinting of ballots. The state Republican Party would choose another candidate to run against Democratic Sen. Claire McCaskill, considered one of the most vulnerable senators in the country.
The National Republican Senatorial Committee headed by Cornyn has advised Akin that it will not support his campaign if he stays in the race, a source from the group told CNN.
Certain GOP nominee Mitt Romney told National Review Online the comments by Akin were "insulting, inexcusable, and, frankly, wrong."
"What he said is entirely without merit and he should correct it," Romney said, according to the website.
And President Barack Obama told reporters that Akin's remarks were "offensive" and didn't make sense.
Akin's remark has also focused new attention on the Republican platform committee meeting in Tampa, where party leaders will hammer out the GOP's stance on key issues, including abortion, ahead of next week's Republican National Convention.
The platform draft, closely guarded by party officials but provided to CNN by a Republican source in Tampa, endorses "a human life amendment" to the Constitution that would outlaw abortion. No explicit exemptions are made for rape or incest.
The document contains language similar to the platforms that were adopted by the party at their conventions in 2000, 2004 and 2008.
But the Romney campaign said Sunday the former Massachusetts governor and his running mate, Rep. Paul Ryan of Wisconsin, "would not oppose abortion in instances of rape."
Meanwhile, a last minute decision by Akin to cancel a primetime TV appearance Monday on CNN's "Piers Morgan Tonight" created a flurry of comments on Twitter, regarding the snub. Instead of Akin, viewers saw an empty chair.
"Congressman, you have an open invitation to join me in that chair whenever you feel up to it," Morgan said. "Because if you don't keep your promise to appear on the show, then you are, what we would call in Britain, a gutless little twerp."
McCaskill also was booked to appear on the show, but canceled earlier in the day.
Following his remark, Akin apologized saying he meant to say "forcible rape" and acknowledged that women "do become pregnant" during such instances.
But Akin insisted he would continue to pursue his Senate bid. On Twitter, he called on supporters to donate to his campaign.
"This campaign is more than just one TV interview," he said on Sean Hannity's syndicated radio show.
CNN's Tom Cohen, Peter Hamby, Paul Steinhauser, Kevin Liptak, Dana Bash, Chris Welch and Ashley Killough contributed to this report.