SOMERSET, Pa. — Former Pennsylvania Sen. Rich Santorum says he's running for president.

Appearing on ABC's "Good Morning America" Monday morning, Santorum said, "We're in it to win it."

The former No. 3 Republican in the Senate, Santorum has been a favorite among the GOP's anti-abortion rights bloc and has been identified with a number of causes embraced by social conservatives.

In his network interview, Santorum appeared in front of a banner-draped setting in Somerset, Pa., where he will make the formal announcement later Monday. Santorum used his brief appearance to criticize President Barack Obama's foreign policy, saying among other things he believes Obama has gone too easy on Iran, which is suspected of trying to obtain nuclear weapons.