Senate Republican Conference Chairman Lamar Alexander will travel Friday to Delaware to campaign for tea party favorite Christine O’Donnell in her uphill Senate race against Democrat Chris Coons.

O’Donnell “will help provide a badly needed check and balance on a runaway federal government that has given us too much spending, too many taxes, too much debt and too many Washington takeovers,” the Tennessee Republican said in a statement.

Alexander is scheduled to attend an event with O’Donnell in the morning, a Republican operative said, although the location and other details were unclear.

Alexander and other top Republicans have been criticized by some tea party activists and bloggers for what they perceive as tepid support for O’Donnell and hard-line conservative candidates, particularly in cases where they beat out establishment-backed candidates during the primaries. O’Donnell surprised Republicans when she defeated Rep. Mike Castle in the GOP primary last month.

Republican operatives dismissed the complaints, arguing that the criticism is misplaced. For instance, one operative noted that Alexander has given O’Donnell $10,000 from his political action committee, and that he and other leaders have backed outsider candidates this year.

Alexander decided to stump for O’Donnell to “encourage support for her candidacy,” the operative said.