Mitt Romney really stepped in it in Iowa.

Gov. Mitt Romney has apologized for referring to the troubled Big Dig construction project as a “tar baby” during a fundraiser with Iowa Republicans, saying he didn’t know anyone would be offended by the term some consider a racial epithet.

In a speech Saturday, Romney, a Republican considering a run for president in 2008, acknowledged he took a big political risk in taking control of the project after a fatal tunnel ceiling collapse, but said inaction would have been even worse.

“The best thing politically would be to stay as far away from that tar baby as I can,” he told a crowd of about 100 supporters in Ames, Iowa.