Said spokeswoman Jen Psaki of Romney: "It is perplexing that he wouldn't demand to have that ad taken down."
Another tea party-backed candidate, Rep. Joe Walsh, R-Ill., said last week that medical advances mean women no longer die in pregnancies and the exceptions for abortion are unnecessary. The American College of Obstetricians and Gynecologists called that comment inaccurate since "pregnancy is not a risk-free life event." The organization said more than 600 women die each year from pregnancy or childbirth-related reasons.
As for Mourdock, the National Republican Senatorial Committee stood by its candidate and argued that his words were being taken out of context.
"Richard and I, along with millions of Americans - including even Joe Donnelly - believe that life is a gift from God. To try and construe his words as anything other than a restatement of that belief is irresponsible and ridiculous," said Sen. John Cornyn, R-Texas, chairman of the committee.
Senate Minority Leader Mitch McConnell, R-Ky., said it is "incredibly irresponsible for anyone to take what Richard said about his views on life to demean his opposition to the detestable act of rape."
Cornyn had criticized Akin in August and called on him to abandon the Missouri race at a time when the GOP had a chance to put a replacement candidate on the ballot. Republicans have no opportunity now to make a change 13 days to the election in Indiana.
This month, the Republican Senatorial Committee has spent more than $1.2 million on ads criticizing Donnelly. The Republican-favoring group Crossroads GPS invested nearly $1.1 million on Wednesday to run ads against the Democrat.
In the most competitive Senate races, however, Republicans were quick to react negatively.
In Arizona, Republican Rep. Jeff Flake's campaign said his "pro-life position has always included exceptions for rape, incest and to protect the life of the mother, so he does not agree with some of the comments made by other candidates on this issue."
Still, Flake's rival, former U.S. Surgeon General Richard Carmona, tried to use the firestorm over Mourdock's remark in the Arizona race.
"Jeff Flake's record is in lockstep with the ignorant and dangerous comments and positions we've seen come from U.S. Senate candidates across the country," said Elizabeth Kenigsberg, a Carmona campaign spokeswoman.
In Nevada, Republican Sen. Dean Heller also disagreed with the comments from Mourdock. Heller is in a close race with Democrat Shelley Berkley.