The committee will withhold $5 million in planned spending on TV advertising in Missouri if Akin does not step aside, a committee official said.
"I recognize that this is a difficult time for him, but over the next 24 hours, congressman Akin should carefully consider what is best for him, his family, the Republican Party, and the values that he cares about and has fought for throughout his career in public service," Cornyn said.
Republican National Committee Chairman Reince Priebus, asked whether Akin should drop out of the Senate race, told CNN: "If it was me, I would step aside and let someone else run for that office." Priebus condemned Akin for a "bizarre statement" that is "biologically stupid," and said he would prefer if Akin not attend the Republican National Convention next week.
Democrats used the Akin remarks as evidence that Republicans are waging a "war on women," largely over birth control.
"Rape is rape," Obama said. Akin's comments underscore "why we shouldn't have a bunch of politicians, a majority of whom are men, making health care decisions on behalf of women," he said.
Akin, a Tea Party-backed conservative who opposes abortion, caused an uproar when he said in the interview that the need for abortions in the case of rape was "a particularly tough ethical question."