BOSTON (AP) -- Elizabeth Warren is receiving the backing of former President Bill Clinton.

In a letter to Warren supporters Wednesday, Clinton warned that re-electing Republican U.S. Sen. Scott Brown could turn the Senate over to a party he said is "controlled by right-wing Republicans and Tea Party radicals."

Clinton says one way to keep a Democratic majority in the Senate is to elect Warren.

Clinton is a major figure when it comes to energizing Democratic voters. He's also taken to the campaign trail on behalf of President Barack Obama.

A Brown spokesman called Clinton's endorsement "ironic" given Warren's legal work for LTV Steel as it fought a mandate to pay additional money into a health care fund for retired coal miners.

Warren's campaign has said there was never any question miners would receive full benefits.