Former Montgomery County executive Douglas M. Duncan (D) said Tuesday that he had decided against making a run for the redrawn 6th Congressional District seat, and he is leaning toward backing financier John K. Delaney for the post instead.

Duncan’s name has been in the mix of potential candidates since the 6th, currently occupied by Rep. Roscoe Bartlett (R), was redrawn to include the western portion of Montgomery County, making it much more amenable to Democrats. Though the district was drawn in a way that excluded Duncan’s Rockville home, he served in the county’s top post for 12 years and could have brought strong name recognition to a congressional campaign.

But in an interview Tuesday morning, Duncan said he had decided against throwing his hat in the ring.

“I looked at the race very closely and thought about it for some time,” Duncan said. “In the end I decided I’m an executive, not a legislator.”

State Sen. Robert J. Garagiola (Montgomery) is already in the race for the Democratic nod, and Delaney — a Potomac resident who serves as chairman of the Chevy Chase investment firm CapitalSource — announced Monday that he was forming an exploratory committee. Former Montgomery County Council member Duchy Trachtenberg (D) is also running.

Maryland Senate President Thomas V. Mike Miller Jr. (D-Calvert) is a close Garagiola ally and helped draw the district with him in mind. Duncan suggested that could backfire on Garagiola.

“I think it’s going to be an interesting race,” Duncan said. “There is some resentment with how the district was set up, particularly in western Maryland, and I think Garagiola is going to have problems with that.”

So Duncan sounds likely to back Delaney, a wealthy political novice, instead.

“I’m talking with him,” Duncan said of Delaney. “There’s nothing formal, but I’m looking to find a way to help him.”

But Garagiola’s campaign fired back, suggesting he has a much better profile for the district than Delaney does.

“Rob’s experience creating jobs is already gaining him support in Western Maryland,” said Garagiola campaign manager Sean Rankin. “Now voters throughout the district will have a clear choice between a veteran with a proven track record of fighting for middle-class families or an unvetted big banker.”