According to the Times, the White House and Boehner are still in communication with party leadership in the House and the Senate, but the exclusion is meant to improve the negotiations:
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All sides, even the parties excluded, say clearing the negotiating room improves the chance of success. It adds complexity as the two negotiators consult separately with the leaders not in the room. But it also minimizes the number of people who need to say yes to an initial agreement. […]
The exclusion of Senators Reid and McConnell and Ms. Pelosi, the House Democratic leader, is a departure from last year’s search for a major deficit deal. Then, Obama-Boehner deficit talks coincided with side talks between Vice President Joseph R. Biden Jr. and Representative Eric Cantor of Virginia, the House majority leader, which were followed by broader talks by a special bipartisan Congressional committee. All failed.
This time, while Mr. Boehner has made himself the sole focal point, aides say he has made sure a broad leadership team is behind him. He meets every morning while the House is in session with the full slate of Republican leaders, as well as the committee chairmen who would most likely implement a deal: Representative Paul D. Ryan of Wisconsin, who heads the Budget Committee; Representative Dave Camp of Michigan, who leads the Ways and Means Committee; and Representative Fred Upton of Michigan, who heads the Energy and Commerce Committee.
Despite the arrangement, Boehner said in a Friday press conference that negotiations have not improved this week.