The Senate Democratic Policy and Communications Center faces fresh scrutiny following the departure of the communication war room’s most senior aide to Majority Leader Harry Reid.

The unusual marriage of the Nevada Democrat’s communications staff with that of Conference Vice Chairman Charles Schumer — charged with the running the DPCC — has from the beginning fueled speculation about Reid’s hold on power and whether his New York colleague would use his expanded responsibilities to solidify his influence over the caucus. Last week’s decision by Reid’s chief spokesman, Jon Summers, to quit after just five months on the job has helped resurrect such questions, although the factions involved dispute the connection.

Two Democratic sources with knowledge of the inner workings of the DPCC said Summers is leaving in part out of frustration, arguing that while the organization is populated with Reid staff and the Majority Leader participates in decision-making, Schumer and his staff ultimately determine strategy and exert more influence.

“It’s hard to be a Reid island in a sea of Schumer,” one source said.

Summers flatly dismissed that contention. More campaign strategist than Capitol Hill operative by nature, he is headed to a political consulting firm with ties to Reid.

“It’s a fantastic opportunity for me, and it’s the place I’ve thought for quite some time I’d like to work for when I decide to leave the Senate,” said Summers, who will become a vice president with GMMB. Summers played an integral role on Reid’s difficult but ultimately successful 2010 re-election bid before taking up residence in the DPCC.

Another Senate Democratic leadership aide refuted suggestions that Reid and Schumer staffers have been engaged in a daily struggle for control of DPCC strategy and operations, noting that while the Conference vice chairman runs the caucus message center, nothing happens without the Majority Leader’s sign-off. The structure of the DPCC is set to remain the same when Adam Jentleson, Summers’ deputy in the war room, takes over as Reid’s chief spokesman when Summers officially departs in July.

“There is a mutual respect and sense of cooperation that has made the DPCC more successful and productive than people might have thought given how unorthodox it is,” the Democratic leadership aide said Monday.

The DPCC, a merger of Reid’s press war room from the 111th Congress and the old Democratic Policy Committee, was created late last year in the wake of Conference discontent over the way the health care debate was handled and the subsequent results of the 2010 elections. The operation was designed to be run jointly by Reid and Schumer staff, plus aides to DPCC Vice Chairwoman Debbie Stabenow (Mich.). But from the beginning, the DPCC has clearly been a Schumer operation.

Top Schumer aide Katie Beirne serves as DPCC staff director, with another top aide to the Senator, Brian Fallon, holding the title of DPCC chief spokesman. Jim Manley and Rodell Mollineau, who had been Reid’s top two communications operatives on Capitol Hill and in charge of the Majority Leader’s press war room, decided to leave earlier this year. Summers was essentially hired to replace them.

The DPCC was formed to help Senate Democrats achieve more message cohesion and remain on the offensive against Republicans after an election cycle in which the majority often felt outmaneuvered by the GOP.

The organization’s goal is to coordinate message and legislative strategy, provide Members with the tools that they need to communicate with voters and put Republicans on the defensive in their home states. The DPCC has moved in particular to bolster the political prospects of those Democrats on the ballot in 2012, making it a point to let them enjoy the press spotlight on subjects that could improve their electoral prospects.

The Democratic leadership aide said the mission of the DPCC is to “emphasize the caucus as a whole,” asserting that the Conference is generally pleased with the performance of the new war room, now in its seventh month of operation.

“If you surveyed the caucus, the overall impression would be that the messaging operation is more responsive, aggressive and Member-friendly than it’s ever been,” the leadership aide said.

But the DPCC has its critics, including some who view the operation simply as a Schumer vanity project that is being used as a means to acquire power. One Democratic strategist said pointedly that Summers’ exit from the DPCC was part of the continuing “Schumerization” of the war room.

“The war room just got ‘Schumed,’” the strategist said. “Schumer’s got the best of both worlds. He’s got more and more of a role in shaping the message, and he doesn’t have any of the responsibility and accountability that comes from being the leader.”