It looks increasingly as if Democrats have a dogfight on their hands in suburban Philadelphia's Sixth Congressional District.

Rep. Chris Carney (D., Pa.) announced yesterday that he was endorsing Manan Trivedi, a Reading doctor and veteran of the current Iraq war, in the primary. Carney is the first member of the state's congressional delegation to back Trivedi.

Carney praised Trivedi's "admirable dedication to service."

Former Inquirer editorial writer Doug Pike declared his candidacy in April, hoping to cinch the nomination with personal wealth and a pile of endorsements. Since Trivedi entered the race in September, after leaving the Navy, the two have battled for support and cash.

The idea: Demonstrate viability to the Democratic Congressional Campaign Committee and national party donors. The seat will be open in 2010 because Republican Rep. Jim Gerlach is running for governor.

Yesterday the Pike campaign rolled out a nod from Rep. Nikki Tsongas (D., Mass.) as its latest entry in the endorsement arms race.

And Lower Merion Township Commissioner Brian Gordon said he was actively exploring a primary bid. "Democrats want someone to win," said Gordon, who just won his second four-year term. He described himself as "fiscally moderate to conservative and socially progressive," which he said was a good match for the district.

In the area congressional delegation, Pike boasts the support of Democratic Reps. Bob Brady, Chaka Fattah, Allyson Y. Schwartz, and Patrick Murphy. Pike is the son of former Rep. Otis Pike of New York.

Carney, elected in 2006, represents the 10th District in Northeast Pennsylvania; he is a commander in the Naval Reserve.

Trivedi, a former lieutenant commander in the Navy, served as a battalion surgeon with the Marines in Iraq.

In the last two weeks, his campaign has announced the support of 40 party committee people in the district, which covers parts of Montgomery, Chester, Berks and Lehigh Counties.

One of them, Fred Sheeler, the Berks County recorder of deeds, had initially endorsed Pike, then switched. State Sen. Daylin Leach (D., Montgomery) earlier had withdrawn his Pike endorsement and declared himself neutral.

Meanwhile, Pike landed two big Pennsylvania fund-raisers: Richard Schiffrin, national finance cochairman for Hillary Rodham Clinton's presidential campaign last year, and lobbyist Bill Titelman.

"It's a competitive primary, and we're not taking anything for granted," said Andrew Eldredge-Martin, Pike's campaign manager.

Pike raised $902,000 through Sept. 30, of which $620,000 was his own money. Trivedi raised $127,000.

Contact staff writer Thomas Fitzgerald at 215-854-2718 or tfitzgerald@phillynews.com.