With the Maryland congressional primary just five weeks away, two well-funded Democratic heavyweights have been busy attacking each other in the newly competitive district held by Republican Rep. Roscoe Bartlett.

But even as state Sen. Rob Garagiola and financier John Delaney have sucked up much of the political oxygen, a third candidate has quietly collected some grass-roots support.

Milad Pooran, a doctor in the U.S. Air Force Medical Corps, has been a favorite of some activists, earning more attention in the blogosphere than in the mainstream media. And now he is picking up the backing of some prominent liberals, including former Democratic National Committee chairman Howard Dean and Reps. Raul Grijalva (Ariz.) and Keith Ellison (Minn.), co-chairs of the Progressive Caucus.

Dean, noting that he is a fellow doctor, said in a news release issued by the Pooran campaign he was backing Pooran because “[t]here is only one true progressive in the Democratic primary, and only one candidate who can win in November.”

Five Democratic candidates are on the ballot in the 6th District, which now includes a slice of Montgomery along with rural western Maryland. Pooran said he wasn’t surprised that Garagiola and Delaney were drawing so much of the focus.

“Certainly Senator Garagiola gets a lot of attention because of his position in the Senate, and John Delaney gets a lot of attention because of his money,” Pooran said. “We’ve always been trying to talk about ourselves.”

However many endorsements Pooran collects, he faces some disadvantages. Through Dec. 31, he had raised $108,000, while Garagiola had banked $344,000. Delaney, meanwhile, reported raising $118,000, but he is wealthy and expected to put upward of a million dollars in the race from his own pocket.

Garagiola also will benefit from the muscle of organized labor and from the support of party establishment figures.

Neither Garagiola nor Delaney seems concerned about Pooran. When Delaney’s campaign circulated a recent internal poll, it did not include Pooran in its hypothetical matchups.

Pooran, for his part, said he “wouldn’t vote for these two other guys” if he wasn’t running. So if he loses the primary, will he pledge to support the Democratic nominee? “I’m going to say that’s a theoretical question,” Pooran said, “and one I hope I won’t have to answer.”