MADISON, Wis. -

President Barack Obama has added his voice, virtually, to the Wisconsin recall election fight, sending out a timely tweet backing Democrat Tom Barrett.

The president wrote late Monday on Twitter, the social media site for micro-blogging: "It's Election Day in Wisconsin tomorrow, and I'm standing by Tom Barrett. He'd make an outstanding governor. -bo"

Barrett is seeking to replace Gov. Scott Walker in Tuesday's recall election, which was sparked by Walker's successful push to strip public sector unions of most of their collective bargaining rights.

While many prominent Democrats, including former President Bill Clinton, campaigned for Barrett, Obama mostly kept his distance.

White House press secretary Jay Carney was asked Monday why the president wasn't campaigning for Barrett. Carney said Obama "supports him" and hopes he wins.