Updated 2:42 p.m. ET

GOP presidential hopeful Herman Cain is trying to tamp down controversy over his comments about abortion.

"I'm 100% pro-life. End of story," he tweeted.

Cain's comment in a CNN interview that decisions about abortion should be left to women and their families raised eyebrows and drew a rebuke from rival Rick Santorum.

The interview also touched on Cain's views about homosexuality.

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GOP presidential hopeful Herman Cain told CNN last night that homosexuality is a choice and his stance against abortion should not be a "directive" to the nation.

The comments by Cain, who is essentially tied with Mitt Romney at the top of recent national polls for the GOP nod, could get further scrutiny in early states such as Iowa and South Carolina where social conservatives play a key role in picking a nominee.

"Although people don't agree with me, I happen to think that it is a personal choice," Cain said about homosexuality in the Wednesday night interview.

When CNN host Piers Morgan said he believed Cain's comments were akin to a gay person telling the candidate that he chose to be black, Cain responded: "You know that's not true. I was born black," adding his race "doesn't wash off."

On another hot-button topic, Cain said he believes life "begins at conception" and "under no circumstances" does he support abortion.

But he seemed to qualify his opposition by saying the decision on whether to have an abortion comes down to a choice by a woman and her family.

"I can have ... an opinion with it being a directive to the nation," he said. "The government shouldn't be trying to tell people everything to do, especially when it comes to social decisions they have to make."

GOP presidential rival Rick Santorum, a favorite of social conservatives, blasted Cain for trying to have it both ways on abortion.

"I find it gravely troubling that Herman believes it's a life, but that he doesn't consider it a life worth fighting for," Santorum said in a statement. "You cannot be both personally against abortion while condoning it -- you can't have it both ways. We must defend the defenseless, period."