Under the deal that Washington lawmakers have finally taken up, the majority and minority leaders from the House and Senate will each appoint three members to sit on the 12-member Joint Congressional Committee, which must come up with $1.2 trillion to $1.5 trillion in savings by Thanksgiving. “Who they appoint will determine how serious they are about succeeding,” says Maya MacGuineas, president of the Committee for a Responsible Federal Budget. “If it’s people who have no intention on working toward a deal — the equivalent of a poison pill — it ends everything right there.”

Given the stakes, both parties will want to appoint members who have close ties to the leadership and are willing to carry out their directives. “Budgeting is the most political of all procedures on the Hill,” says Stan Collender, a former congressional budget analyst. And the stakes this time around are even higher. Committee chairs and ranking members who work closely with taxes, health care and entitlements will all be strong contenders. But congressional leaders will also probably steer clear of members up for a tough reelection battle in 2012, such as Sen. Orrin Hatch, ranking member of the Senate Finance Committee.

Republicans, for their part, are unlikely to appoint anyone who’s publicly supported including revenue as part of a debt deal, namely in the form of tax increases. That would eliminate even fiscal hawks such as Sen. Tom Coburn, who’s made new enemies on the right by saying revenue should be on the table. Many Hill watchers expect the GOP to appoint Rep. Paul Ryan, whose original 2012 budget plan set the hard-line tone for the incoming House Republicans.

Other likely contenders include Sen. Jon Kyl, the minority whip who’s part of the Senate GOP leadership and is retiring in 2012, and Rep. Dave Camp, the staunch conservative chairman of the House Ways and Means committee. There are also members with a better record of working across the aisle: Sen. Mike Crapo, for example, backed the Bowles-Simpson debt commission’s findings, but his very association with such efforts and the recent Gang of Six talks might also make GOP leaders more wary. “No one from the Senate Gang of Six, who proposed tax increases, need apply,” the Wall Street Journal opined. “The GOP choices should start with Arizona Senator Jon Kyl and House Budget Chairman Paul Ryan, adding four others who will follow their lead.”

On the Democratic side, fiscal hawks and centrists will probably back Senate Finance Committee Chairman Max Baucus, a member of Vice President Biden’s working group. Along with his Democratic colleagues in the Biden group, Baucus was willing to discuss painful spending cuts to Medicaid and food stamps while raising concerns about the impact of such changes to seniors and low-income Americans, according to sources close to the talks.

Democrats might feel less wary about Sen. Dick Durbin, who backed Bowles-Simpson — establishing his deficit-slashing cred — but who was also reportedly key in pushing the Gang of Six talks this summer to the left. “He’s been in the room a lot,” says Collender. Sen. Kent Conrad, a noted budget wonk, is also retiring next year, but his independent views might make him “a bit too much of a wild card,” he adds. Liberals will want to see the likes of Sen. Tom Harkin and Sen. Sherrod Brown on the committee. “Unfortunately, I don’t think the leadership will allow this,” says Dean Baker, an economist at the Center for Economic Policy Research. “I worry that the Dems will be the usual suspects, starting with the Gang of Six crew.”

On the House side, the Democrats choices will probably tilt more to the left: Many observers expect Minority Leader Nancy Pelosi to choose Rep. Chris Van Hollen, a leading voice as a member of the Biden deficit group and a Democratic Party stalwart. Moderates will want the likes of Steny Hoyer, the more fiscally conservative minority whip. But Pelosi will be under intense pressure by her caucus to pick more reliably liberal members, given how much the deal has already infuriated the party’s progressive caucus.

Given the political stalemate over the debt ceiling — and the torturous debate that’s accompanied it — many are highly skeptical that the Supercommittee will agree to come up with the required savings, even with the threat of triggered cuts overhead. Even if the appointed members are individually willing to work across the aisle, Republican leaders will make sure their Supercommittee members don’t budge on taxes. “And if taxes can’t be part of this equation, why would Democratic leaders appoint members who agree to major mandatory cuts? We’re right back to where we’ve been,” notes Bill Hoagland, a former chief of staff to GOP Sen. Pete Domenici.

But others are still holding out some hope for the Supercommittee – at least until the members are announced. “I don’t think it was created to be serious, but this moment is so serious that despite itself, the committee might produce something serious,” MacGuineas says.

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