Senate Democrats re-elected Majority Leader Harry Reid to another two-year term Tuesday, but the Nevada Democrat still faces an unhappy caucus determined to force changes in the way the chamber operates as 23 of them prepare to face voters in 2012.

In the past two weeks, Reid has been trying to show he’s learned the lessons of a midterm rout that cost Democrats control of the House and six seats in the Senate.

But Democrats spent the morning and afternoon Tuesday not just electing Reid and their slate of leaders for another term, but also “airing grievances,” as one Senate Democratic source put it.

Those grievances primarily came from the very rabble-rousers who demanded that Reid needed to better coordinate political, policy and message strategy in the next Congress — Members who were elected in 2006 and 2008.

“There are a lot of boils to be lanced,” one Senate Democratic aide said. “The truth is that anytime there’s a diminution in the ranks … especially with 23 [Democrats] up, you’re going to have people who are going to say, ‘What happened last time can’t happen to me.’”

The key, the aide said, is including Members in more of his policy and political decisions.

“Not being heard in the process, that’s what is driving them nuts,” the aide said.

Reid has already announced he is making major changes designed to better coordinate political messaging with policy, but junior Members of the Senate Democratic Conference continued to tell him Tuesday that won’t be enough to satisfy their concerns about the direction of his leadership in the 112th Congress.

“We have 23 Members of our caucus that have been elected since 2006. That’s a huge number, and that bulge is pushing a little bit on some reform,” said Sen. Claire McCaskill (D-Mo.), who faces her first re-election in 2012. “And in fairness, the more senior Members have been great about some of the things we’ve asked be put on the table, and I think we’re going to see some changes.”

Of course, a linchpin of Reid’s ability to ensure the political well-being of the 43 percent of the caucus up for re-election is finding someone to head the Democratic Senatorial Campaign Committee. The task has confounded Reid for weeks as Member after Member has declined to take on the weighty job. A new chairman was supposed to have been named Tuesday, but the announcement was postponed.

Meanwhile, Reid’s defenders note that he was re-elected as leader precisely because he has been willing to facilitate changes to caucus operations.

One major demand of the ’06 and ’08 classes on Tuesday was to have more influence and ownership of legislation moving through the chamber in an attempt to dilute the power of committee chairmen. Reid gained the Democratic leader spot in 2004 after promising many chairmen he would defer to them on most issues.

Members of the junior classes met Monday in defiance of Reid, after he rebuffed their request for a two-day retreat to discuss caucus politics, the Senate aide added. And they came well-prepared to Tuesday’s meetings with requests for more influence on committees, more productive caucus meetings, and changes to the Senate’s work schedule so it might be more efficient.

“Some say the process and procedure are secondary, but if you improve those and make adjustments, your policy’s going to be better,” said Sen. Bob Casey (D-Pa.), a member of the 2006 class. Democrats are expected to meet again Wednesday and Thursday to continue discussions, including their priorities for the agenda in the lame-duck session.

Senate Majority Whip Dick Durbin (D-Ill.) acknowledged that leaders were dealing with demands for more changes and that some of the discussion revolved around giving junior Members more of a say in the legislative process and more authorship of bills.

“We’re finding way to utilize the talents of all of our Members,” he said.

On Monday, Reid alerted colleagues that he will transfer control of messaging and policy coordination to his No. 3 lieutenant, Sen. Charles Schumer (D-N.Y.), and that he will switch out his chief of staff. He also elevated 2008 class member Sen. Mark Begich (D-Alaska) to the new No. 5 leadership spot: chairman of the Democratic Steering and Outreach Committee.

One senior Senate Democratic aide said the changes show that Reid’s eye is focused on 2012 and the challenges the next two years will present. The aide noted the large number of Democrats seeking re-election, as well as the fact that Republicans have much stronger hands to play in the House majority and in a bigger Senate minority.

“There are things that Reid does extremely well. … It’s going to be increasingly difficult to get pieces of legislation through the House to the president and that’s where Reid’s focus is going to be,” the aide said. “At the same time, there will be a senior Senate Democrat [Schumer] who will be thinking every day about how to coordinate our policy and political message.”

The aide added that Reid also anticipates that the White House will be just as “ineffective” as they were during the past two years, but perhaps more so during the 112th Congress, because President Barack Obama will be focused on his own re-election.

“This is about making sure Obama’s got a majority to come back to when he gets re-elected,” the aide said.

The challenges Reid faces are nothing new. Junior Democrats fought for a more offensive message strategy after a bruising health care reform debate, and they took up filibuster reform once they grew frustrated with the slow pace of the chamber.

Sen. Tom Udall (D-N.M.) said Tuesday he has been broadening his coalition of filibuster reform supporters for the next Congress to include a few Republicans. McCaskill said getting a vote during the lame-duck session to restrict “secret holds” is “on my Christmas list.”

“I think it’s important to be willing to rock the boat for reform in the institution,” she said.

Sen. Amy Klobuchar (Minn.) has taken the lead for the first-term Members in creating a filibuster reform proposal the entire Democratic caucus might support. Sen. Benjamin Cardin (Md.) is doing the same for caucus rules, working to compile a list of changes that can be adopted for next year.

But it was unclear when the caucus might vote on the proposals.

“I think it’ll depend on the consensus-building meetings we’ll have this week,” Udall said. “It’s going to be a work in progress for a while.”