WASHINGTON – Virginia Gov. Bob McDonnell put his support behind Massachusetts Gov. Mitt Romney, one of only two Republicans who qualified for Virginia’s ballot.

McDonnell tweeted his endorsement Friday morning.

National party leaders have been slow to back Romney in his GOP bid for the White House.

The endorsement comes as Romney heads into his final full day of campaigning in South Carolina.

Follow WTOP on Twitter.

(Copyright 2012 by WTOP. All Rights Reserved.)