Republicans on Sunday sought to defend a plank of their party's platform that expresses opposition to abortion and does not address exceptions for cases of rape and incest.

(Alex Wong/Getty Images)

"That [language has] been there for 30 years," said Virginia Gov. Bob McDonnell (R), on ABC's "This Week With George Stephanopoulos."

"There are multiple human life amendments that were introduced 20, 30 years ago. Some of them had exceptions, some of them didn't," said McDonnell, who is chairman of the party's platform committee. "The real point is, we are affirming that we're a pro-life party.  The details certainly are left to Congress and ultimately to the states and the people on how they ratify such an amendment, or more importantly, what they do at the state level."

"The platform of the party hasn't changed," chimed in former Florida governor Jeb Bush (R) on NBC's "Meet The Press."

The Republican platform committee last week adopted a plank that calls for a constitutional amendment protecting “human life." Exceptions for rape and incest were not included. Mitt Romney, the presumptive GOP presidential nominee, opposes abortion, but favors exceptions in cases of rape and incest.

Los Angeles Mayor Antonio Villaraigosa, the Democratic National Convention chairman, countered McDonnell by pointing to what former Florida governor Charlie Crist wrote in a Sunday Tampa Bay Times op-ed endorsing President Obama's campaign. Crist, who left the Republican party during his 2010 Senate campaign to run as an independent, wrote that the GOP has adopted far-right positions on important issues that hinder its ability to govern. "Look no further than the inclusion of the Akin amendment in the Republican Party platform, which bans abortion, even for rape victims," Crist wrote, referring to Rep. Todd Akin's (Mo.) recent controversial comments about rape and abortion.

"With respect to the plank, I think Governor Crist said it very well, and that is what it is," Villaraigosa said on ABC. "And maybe it's been there for 30 years, but it's time to take it out.  The idea that we put in our U.S. Constitution an amendment that says that women can't get an abortion even in the case of incest and rape is way beyond the mainstream."

McDonnell sought to downplay the significance of Crist's endorsement of Obama, arguing its influence would be minimal.

"I would say that Governor Crist's endorsement adds one more vote in Florida, and that's it. He is wrong on every other point," McDonnell said.