President Barack Obama will push through his bipartisan debt commission by executive order Thursday, but it remains to be seen whether the panel will actually have Republican members.

Neither Senate Minority Leader Mitch McConnell (R-Ky.) nor House Minority Leader John Boehner (R-Ohio) has appointed commissioners to the panel—and aides to both said they are waiting for more details about the panel before deciding whether to participate.

The panel’s structure remains murky, but Hill aides said Republicans were asked to name six of the panel’s 18 members, with McConnell and Boehner being tapped to name four of them. The White House and Congressional Democrats are picking the rest.

Obama already announced who will lead the panel: University of North Carolina President Erskine Bowles, a Democrat, and former Wyoming Sen. Alan Simpson, a Republican. But beyond naming the co-chairmen, the White House is keeping mum on other details about the commission, including its membership.

White House Press Secretary Robert Gibbs on Wednesday dodged questions about whether Republicans had committed to the panel. He said he didn’t know whether the White House was calling GOP leaders Wednesday to press the issue, although calls were made last week.

“What the Republicans decide to do is largely up to them. … We’ll see. I think they understand the seriousness with which the president looks at this effort and attaches bipartisan leadership to, and we’ll see where they go from here,” Gibbs said during his daily briefing.

Further fueling speculation on GOP participation, Gibbs said Obama would not announce the panel’s membership during Thursday’s unveiling. Instead, he will simply announce the co-chairmen and the structure of the commission and sign the executive order.

“We just haven’t announced [the members]. But we will. … It will be interesting to see what the Republican reaction is” to the commission being announced, he said.

Gibbs highlighted that McConnell and Boehner initially supported a similar commission proposed by Senate Budget Chairman Kent Conrad (D-N.D.) and ranking member Judd Gregg (R-N.H.). But that commission failed to advance because of later opposition from Republicans including McConnell — a move the White House chalked up to partisan politics.

Obama was hoping Congress would set up the commission but “that, for political reasons, failed. He’s taken the step of setting this up through an executive order because he’s serious about making progress on this issue,” Gibbs said.