WASHINGTON (AP) — Sen. John McCain says Rick Santorum should recognize "it's time for a graceful exit" from the Republican presidential campaign in the wake of Mitt Romney's sweep of primaries in Wisconsin, Maryland and the District of Columbia.

McCain also tells "CBS This Morning" there's a strong field of Republicans who could be the vice presidential candidate.

When asked to suggest some names Wednesday, the Arizona Republican said, "I think it should be Sarah Palin." But when pressed to elaborate, he said "I think we have some very qualified candidates," citing Sen. Marco Rubio of Florida and Govs. Mitch Daniels of Indiana, Chris Christie of New Jersey and Bobby Jindal of Louisiana.

Palin, the former governor of Alaska, was McCain's running mate in his unsuccessful bid for the presidency four years ago.