BOSTON (AP) — Democrat Elizabeth Warren is tweaking Massachusetts Sen. Scott Brown for refusing a final debate offer.

The fourth debate was planned for Tuesday, but was delayed because of Superstorm Sandy.

Warren agreed to a Thursday debate, but the GOP's Brown declined. He had twice pledged that a final debate would happen, but a Brown aide said it conflicted with a bus tour he planned for the close of the reelection campaign.

In Warren's new radio ad, a narrator faults Brown for backing out of the debate, saying "rather than discuss the issues, he had to grab a bus" and adding "with his record you can't blame him for hitting the road."

Copyright 2012 The Associated Press.