HARRISBURG — A Democratic political action committee began running TV ads in Pittsburgh on Wednesday to boost Democratic Sen. Bob Casey’s reelection bid against a surprisingly strong challenge from Republican Tom Smith, a tea party favorite who has personally invested more than $16 million into the race.

The Majority PAC ad said Smith’s cost-cutting agenda to eliminate the federal Department of Education would mean less money in classrooms, fewer children in Head Start and less aid for college students.

Smith’s campaign responded that he would help schools by fighting to reduce the cost of the federal government and unfunded mandates, and that he has not ruled out keeping some Department of Education functions.

Smith was on course to outspend Casey by two-to-one after July 1.