For the second time in four years, Senate Majority Leader Harry Reid has expanded the role of one of his closest allies and the caucus’s most ambitious Members — Sen. Charles Schumer.

Reid announced Monday he was giving Schumer, the current No. 3 lieutenant and Conference vice chairman, more control over legislative and communications strategy — a move that dramatically increases the power of a man who has long sought to replace Reid when, or if, the Nevada Democrat steps down.

But the move isn’t just about expanding the New York Democrat’s reach. Reid was also responding to the concerns of rank-and-file Members who have been demanding that he run things differently — and more aggressively — next year.

“What we’re seeing in the House with the Democratic leadership race is similar to what we’re seeing in the Senate,” one Senate Democratic aide said. “Reid, just like [outgoing Speaker Nancy] Pelosi, has the votes to remain Majority Leader. That being said, there is wide discontent among more junior Members of the caucus. More senior Members, especially those who are chairmen of committees, enjoy Reid’s hands-off style. It’s to their benefit. But the younger folks who have had to fight campaigns and come from different schools of messaging and tactics see a real need for change.”

Reid has been dealing with junior Members demanding changes to Senate rules for months; they have also agitated over the past year for the more robust messaging operation. Members of the 2006 and 2008 classes huddled Monday afternoon to plot strategy on how to push changes in Senate rules, including ways to overhaul the filibuster.

Sen. Benjamin Cardin, who was elected in 2006, noted that the coalition of junior Members wields influence because of their size — and because many, including himself, face re-election in 2012.

“I think we have brought an energy to the caucus that’s healthy,” the Maryland Democrat said. Cardin said he has taken a lead role in discussing ways to change rules and procedures within the Democratic caucus.

“You’re going to see more recommendations from us coming,” he said. “There’s a desire to be more effective in some of the things we’re doing. That’s not a criticism of what we’re currently doing, but saying that times have changed and we need to change with them.”

The junior Democratic Members are moving quickly to build support for their efforts. Sen. Chris Coons (Del.) told reporters hours before he was sworn in Monday that he had already been approached by fellow Senators about filibuster reform.

But the biggest change appeared to be Reid’s announcement of Schumer’s new role, which must be ratified by the Conference during today’s leadership elections. Reid, Schumer, Whip Dick Durbin (Ill.), and Conference Secretary Patty Murray (Wash.) are all expected to win election to another two years in their leadership slots. As of press time, Reid had yet to find a taker to helm the Democratic Senatorial Campaign Committee next cycle, when 23 incumbents are up for re-election.

“People generally don’t want the job. It’s not a good job,” the second Democratic aide said.

In a letter Monday to Democrats, Reid said he would merge his own communications “war room” with the legislative operations of the Democratic Policy Committee, and Schumer will be the chairman of the unnamed joint venture. Sen. Debbie Stabenow (Mich.) will serve as Schumer’s vice chairwoman.

Reid, who survived a tough battle for a fifth term, appears to be addressing long-standing Member complaints about the Democrats’ public relations efforts. That criticism that has its roots in the health care reform debate of 2009, when Members felt Congressional leaders and the White House failed to explain the plan to the public.

But the issue reared its head again during a caucus conference call held the day after Democrats lost six seats to Republicans. Though they were relieved that Republicans did not take over the chamber, Members peppered leaders with questions about how they would change to help ensure a better outcome for the nearly half the caucus up for reelection in 2012.

In his letter Monday, Reid wrote that he wants to  “better integrate our legislative- and message-crafting functions into a central, coordinated nucleus managing policy, press and politics.” With DPC Chairman Byron Dorgan (N.D.) retiring this year, the committee and its No. 5 leadership post were open for the taking.

Stabenow and Sen. Sheldon Whitehouse (R.I.) were widely seen as contenders for the DPC chairmanship, and several Democrats speculated the post would go to a more junior Member.

Instead, Schumer would be empowered to do more, considering he does not appear to be stepping down from his other post as the No. 3 Democratic leader.

Though there are some Members of the caucus who think Schumer might be gaining too much influence, others said they were pleased with the move. Schumer is liked and trusted by most of the Members of the 2006 and 2008 because of his role in helping them get elected when he was chairman of the DSCC.

The decision to give Schumer more responsibility comes just four years after Reid rewarded Schumer’s stewardship of the DSCC by creating the vice chairmanship. Schumer acknowledged earlier this month that Reid had asked him to take a third term as head of the DSCC, but that he declined the offer.

“He’s been impressive at amassing not power, but stuff that translates into influence,” another Senate Democratic aide noted.

Schumer also chairs the Rules and Administration Committee, which oversees office space and doles out “hide-aways” in the Capitol for Senators, as well as addressing other mundane, but important, concerns of Senators’ work life. He is also the top Democrat on the Joint Economic Committee and is in line to take the chairmanship this year, but he may need a waiver from the caucus to hold both the Rules and JEC gavels.

He also chairs the Judiciary panel’s Immigration, Refugees and Border Security subcommittee.

Meanwhile, Reid said he has asked Sen. Mark Begich — a Member of the 2008 class — to replace Stabenow as chairman of the Steering and Outreach Committee, which helps dole out committee assignments and leads outreach to independent interest groups.

Appointing the Alaska Democrat to serve in the leadership sent a positive signal to the aggressive junior class, an aide to a junior Member said. Two additional spots could also be offered up on the whip team to Members of the 2006 or 2008 classes. Sens. Kay Hagan (N.C.) and Mark Udall (Colo.) currently serve as deputy whips.