The most powerful Congressional committee ever constructed will hold its first public meeting Thursday amid promises of transparency, but much of the committee’s work is likely to remain out of sight as staffers and committee members hash out their ideas behind closed doors.

The Joint Committee on Deficit Reduction, aka the super committee, has already seen rising pressure to keep an open process and to promptly disclose campaign contributions to committee members.

The first two meetings — an organizational meeting Thursday and a hearing Tuesday — will be public, and several committee members said this week they would like the process to be open.

But even as they nodded to the clamor for public disclosure, both parties’ committee members huddled and war-gamed privately (and separately) Wednesday to prepare for the first public meeting.

“You should have both” public and private conversations, Sen. Rob Portman (R-Ohio), one of the panel members, said in a brief interview Tuesday. Portman said that meetings should be public but noted there is also a role for private conversations between Members and with staff. He said those conversations have already been taking place over the past several weeks.

“The idea is to build some trust,” Portman said.

Indeed, Co-Chairwoman Patty Murray (D-Wash.) said Wednesday that she’s talked more to her co-chairman, Rep. Jeb Hensarling (R-Texas), in the past few weeks than she has to her children.

Murray said a rules package has already been vetted with her Republican colleagues and would be adopted Thursday.

“I think that we all very much recognize that the public really wants us to solve these critical problems in a very serious way,” she said. “We are prepared to do that. … We intend to be working extremely hard over the next 10 weeks to put forward a proposal that helps put our country back on track.”

She added: “We are putting everything on the table and have not ruled anything out.”

Some lawmakers want guarantees that the committee will conduct its business in public — even if that flies in the face of the reality that every deal ultimately is written in a back room.

Three House Members, Reps. Dave Loebsack (D-Iowa), Mike Quigley (D-Ill.) and Jim Renacci (R-Ohio), introduced a bill Wednesday backed by the Sunlight Foundation that would require disclosure of meetings with lobbyists, campaign contributions and three days of public disclosure of any deal before a vote is taken, among other items.

“The super committee has been given unprecedented power to make unprecedented decisions, and we must call for unprecedented transparency,” Quigley said.

Sens. David Vitter (R-La.) and Dean Heller (R-Nev.) separately wrote to the committee urging it to adopt a sunshine rule Thursday that would require any meetings of the committee with a quorum of members to be public and televised. Another rule would require prompt disclosure of campaign contributions to committee members.

“It’s just plain good government for the public to know what special interests are trying to influence the committee,” Vitter said in a statement.

The committee roster includes Sens. John Kerry (D-Mass.), Max Baucus (D-Mont.), Jon Kyl (R-Ariz.) and Pat Toomey (R-Pa.), as well as Reps. Dave Camp (R-Mich.), Fred Upton (R-Mich.), Chris Van Hollen (D-Md.), James Clyburn (D-S.C.) and Xavier Becerra (D-Calif.).

The committee also faces pressures both on what to do — and what not to do — as members must quickly try to agree on an outline for their deliberations. Democrats on the panel have already been pushing for a jobs package in the short run — with Van Hollen tweeting about the need for infrastructure spending to put people back to work — alongside longer-term deficit reduction. Democrats argue that the deficit problems cannot be solved unless unemployment drops and that cutting too quickly would make the economy worse.

GOP leaders, meanwhile, huddled with their picks Wednesday and expressed optimism that the panel would at least meet the requirement for a $1.2 trillion deficit reduction package — and perhaps more.

“We’re committed that this committee get an outcome,” Speaker John Boehner (Ohio) said after the meeting. “We believe that by reducing our debt we create a better environment to create jobs in America. … And we’re encouraging our Members to work hard to get an outcome.”

“Failure is not an option,” Senate Minority Leader Mitch McConnell (R-Ky.) added. “This committee is going to succeed in meeting at least the floor that’s established in the legislation.”

Senate Majority Leader Harry Reid (D-Nev.) said he’s not going to try to “micromanage” the committee and is encouraged by leaders talking about the importance of avoiding the $1.2 trillion spending-cut trigger that would take effect starting in 2013 if the committee fails to reach agreement.

The committee also faces an early test on whether it will tackle the complicated issue of tax reform, which could be the linchpin of whether the panel can reach a grand bargain that truly deals with the long-term fiscal crisis for the coming decades.

Several Senators not on the committee said Wednesday that there simply isn’t time to do a full tax reform package by Thanksgiving. Sen. Orrin Hatch (R-Utah), the ranking member of the Finance Committee, said he wouldn’t want the committee members to do tax reform by themselves even if they could.

The complexity of tax reform had some Senators, including Democrat Ron Wyden (Ore.), speculating that the super committee could devise a future fast-track process, setting the stage for tax reform at a later date.

Humberto Sanchez, Jonathan Strong and David M. Drucker contributed to this report.