Sen. Bob Corker, R-Tenn., said Tuesday that Treasury Secretary Jacob J. Lew has not been “much of a factor” in working with Congress on economic issues, leaving lawmakers to “wonder who the Treasury Secretary is sometimes.”

Corker, speaking to reporters about his concerns regarding the looming debt limit deadline, teed off on Lew, the former White House chief of staff, and took a swipe at his many Sunday talk show appearances over the weekend.

“I hate to be pejorative, but, candidly, I haven’t seen him be much of a factor on anything since he’s been there, so not really,” Corker said when asked whether Lew is “politicizing the debt ceiling.” Lew has issued grave warnings to members of both parties about the economic consequences of Congress failing to extend the nation’s borrowing capacity.

“I mean you have to scratch your head and wonder who the Treasury secretary is some times,” the Tennessee Republican continued. “I understand they are going to send him out sometimes on the Sunday shows the way that they are.”

Corker said he personally takes the debt limit seriously, despite the questions from other GOP colleagues over whether default is a real possibility if Congress fails to raise the debt ceiling.

Corker said he is most worried about Nov. 1, citing a Congressional Research Service report he was holding in his hand at the time that said that date is when a large chunk of the government’s payments come due.

A spokesperson for the Treasury Department did not immediately respond for comment.

Humberto Sanchez contributed to this report.