Sen. John McCain, R-Ariz., faces enormous pressure from social conservatives to ignore his repeated commitment to change the GOP's platform on abortion.

"If he were to change the party platform," to account for exceptions such as rape, incest or risk to the mother's life, "I think that would be political suicide," said Tony Perkins, the president of the conservative Family Research Council, to ABC News. "I think he would be aborting his own campaign because that is such a critical issue to so many Republican voters and the Republican brand is already in trouble."

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A senior Republican close to McCain told ABC News that building a more inclusive GOP is a top priority for the Arizona senator.

But this adviser does not see changing the party platform to include exceptions for rape, incest, and the life of the mother as necessary for achieving that vision.