After six months of largely sitting back and watching how the new Democratic Senate performs, Republican leaders this week will hold a special retreat to begin honing their 2008 message and agenda — one that’s being privately billed as an 18-month “campaign” to reposition themselves to take on the party in charge.

GOP Senators will huddle Wednesday afternoon behind closed doors for the two-hour, Members-only session at 1:45 in the Capitol’s Mansfield Room. Orchestrated by Republican Conference Chairman Jon Kyl (Ariz.), the meeting will serve as both a “mid-year review” for the first session of the 110th Congress and as an open exchange of ideas on reformatting a Republican Party that handily lost the House and Senate majorities in November.

“This is about laying the foundation for rebuilding the party,” said a Republican Senate leadership aide. “This is a group project. No one person can determine this, we all have to come together and agree on it.”

Kyl, in a brief interview Monday, said the session has both a short-term purpose of arming Senators with a message for the upcoming August recess and a broader goal of engaging Senators to game out the party’s strategy for the remainder of the year. He added that Republicans likely will come together again next January to take stock of their message and platform heading into what many anticipate will be another bitter test at the ballot box.

“Going into the election year, it’s important to know what we stand for, not just what we stand against,” he said.

Kyl said that in the first six months of the year, Republicans have had to do little to try to brand the new majority, saying that by pursuing a partisan agenda the Democrats “have returned to form and really defined themselves. We haven’t had to do a whole lot to define them.”

But Kyl acknowledged that Republicans cannot sit by and simply talk about the Democrats’ shortcomings. Senators need to be armed with their own positions and alternatives that reflect the party’s long-standing principles, whether it is over the war in Iraq, an expected omnibus spending package or health care policy.

While Wednesday’s special Republican Conference meeting will serve as mostly a give-and-take forum for the 49 Senators, sources familiar with the planning say it will also play host to presentations from some outsiders, including GOP pollster and adviser David Winston, who also is a Roll Call contributing writer. Kyl and Minority Leader Mitch McConnell (R-Ky.) also are on tap to speak and are likely to deliver their respective assessments of the GOP’s position heading into 2008.

Republican leaders also will urge Senators to use the August recess to further vet ideas — both in policy and message — for how Republicans should approach the remainder of the 110th Congress.

“We were in the majority for pretty much 12 years,” noted a senior GOP Senate aide. “It took an adjustment. But after six months, things are working differently and we need to find those hard line stances that got us into power.”

The uphill battle Republicans face over the next two years is no secret, even with McConnell publicly acknowledging the GOP will be lucky to hold its own in an unfavorable political climate with nearly twice as many Senate seats to defend. Republicans need to stave off potential challenges to 21 seats, including McConnell’s, while Democratic Senate incumbents face re-election in just a dozen seats.

The timing for the the GOP’s Wednesday retreat is noteworthy given Congress is about to break for face time with its constituents for the longest period yet this year. The meeting also comes as the Democratic majority ramps up a summer message that it has racked up a series of critical accomplishments that include passing a minimum-wage increase, higher education reforms and stiffer homeland security protections while continuing to keep pressure on President Bush to end the war in Iraq.

Senate Democrats will try to further build on their theme this week both in message and in practice as they look to leave town having enacted another string of domestic items including a lobbying reform package and an expansion of the children’s health insurance program.

Intentional or not, the Democrats have begun to trumpet their accomplishments just as Republicans further accusations that the majority party is responsible for leading a “do-nothing” Congress for the first quarter of the two-year session. That’s the same message the Democrats found some success in using to rally against the Republicans during the 109th Congress.

Beyond that, however, Republicans have done little to advance a larger message to define who they are as a party and why they should be put back in charge of Congress. Several Republican leadership aides said party leaders wanted to hold off on undergoing any rebranding exercise until after they had adequate time to assess the Democrats’ performance during the first half of 2007.

“It was necessary for us as an opposition party to find out exactly where the Democrats were going to go so we could exploit what we perceive as their mistakes,” said the GOP leadership aide. “So now we have an opportunity to share with the American people what we would do differently and how it would benefit them.”

But Democrats say regardless of how GOP Senators decide to proceed, they aren’t worried that the minority party will create a successful message or policy offensive. So far, Democrats say Republicans have shown little interest in changing their Congressional posture — especially as they try to block passage of the very programs the electorate sought from a new Democratic majority.

“They act as though the November 2006 election never happened,” a Senate Democratic leadership aide said of the GOP. “I’m not sure if they’re tone-deaf or just plain stubborn, but they’ve spent the first half of this year fighting like hell against making any progress on the issues voters care about.”

The Senate GOP’s assessment mirrors similar efforts undertaken in by the then-minority Democrats in recent cycles. Congressional Democrats spent the better part of the 2006 cycle working to unify around their “New Direction for America” platform, which included a series of Democratic priorities the party vowed to enact if given the gavel in the 110th Congress.

And while it remains unclear exactly what the Senate GOP’s next move will be, Republicans acknowledge they need to get to work now if they are to have success heading into next year.

Already, Senate Republicans have spent recent weeks trying to re-engage with their House counterparts on message and overall policy coordination. Republicans are hoping for new opportunities to synchronize across the Dome in the wake of the latest debates on Iraq and immigration that deeply fractured the party.

As part of that effort, GOP Senate and House leaders last week held rare joint pen-and-pad sessions with reporters and a press conference on taxes and spending, while the leadership has had numerous planning sessions on overall party strategy and is orchestrating lawmakers to head to the Senate and House floors to push similar party themes. House Minority Leader John Boehner (R-Ohio) also is expected to join the Senate Republicans’ weekly steering committee lunch this week.

Beyond that, House and Senate leadership offices have sought to coordinate messages on fiscal discipline, the Bush administration’s midterm report on the Iraq troop “surge” and on accusations of Democrats leading the “post office Congress,” as Republicans argue that Democrats have spent the bulk of their time naming federal post offices.

“It’s about strength in numbers — we’re working together rather than trying to do things separately,” said a senior GOP Senate aide.