(Brendan Smialowski/GETTY IMAGES)

With the bipartisan debt supercommittee’s deadline just two weeks away, Sen. John Kerry (D-Mass.) on Tuesday criticized the most recent proposal reportedly made by congressional Republican members, calling the move only a “slight” change from the GOP’s earlier stance on revenues.

“Well, they’re anxious to promote a certain concept with all of you,” Kerry told reporters at the Capitol when asked about reports that Republicans have offered a plan that would increase tax revenue by as much as $300 billion.

“I mean, I’ll be very clear that whatever they put there doesn’t get the job done, and we’ve got some distance to travel, and we’re working very hard to do that,” he added.

A reporter asked Kerry whether it would be fair to characterize the proposal as a “substantial” change in Republicans’ position on tax increases.

“I would not characterize it as substantial yet, but it’s a change,” Kerry responded. “That’s about as detailed as I’ve been this entire time.”

The Post’s Lori Montgomery reported Tuesday afternoon that in a closed-door negotiating session Monday night, Republicans offered a plan that for the first time would have included higher tax revenue but also would have extended the Bush-era tax cuts past 2012. Democratic aides have dismissed the GOP’s reported offer as insufficient.

Asked whether there needs to be new tax revenue, as opposed to non-tax revenue, in a final deal, Kerry said Tuesday that Democrats “have been very clear that there has to be some additional tax revenue.”

“It has to be able to be scored by the (Congressional Budget Office); it has to be measured,” he said. “That requires a certain kind of revenue, and we’ve been very clear from day one. ... Everybody’s working in good faith.”

The bipartisan panel, which initially gave the impression it would conduct most of its proceedings in public, has in recent weeks held most of its negotiating sessions behind closed doors, and it was unclear Tuesday when the panel would hold its next meeting.

“You have to talk to the chairs,” Kerry said when asked whether further sessions were planned for this week. The panel’s co-chairs are Rep. Jeb Hensarling (R-Texas) and Sen. Patty Murray (D-Wash.).

Sen. Charles Schumer (D-N.Y.) this week became the highest-ranking congressional leader to tamp down the expectations for the supercommittee, telling MSNBC’s Joe Scarborough on Monday that he believed the panel would fail if Republicans didn’t agree to include tax increases in a final deal.

Schumer walked back his remarks late Monday, and leaders on both sides of the aisle Tuesday said they remain “hopeful” — although they declined to describe themselves as “optimistic.”

“I’ve said all along, I’ve never characterized anything as optimistic; I’ve said hopeful, and I remain very hopeful,” Kerry said. ”I think the stakes are high enough that the committee needs to meet the challenge, and I’m pushing very hard for us to do that. I think there would be a lot of negative implications of us not achieving the de minimis measure of what we’ve been asked to do,” using a Latin phrase meaning least to the point of inconsequence.

Senate Majority Leader Harry Reid (D-Nev.) said he had spoken with his three appointees to the panel — Kerry, Murray and Sen. Max Baucus (D-Mont.) — multiple times in the past day.

”Any time that Senator Murray says, ‘Give us more time,’ I listen to her,” Reid said Tuesday afternoon when asked whether he’s optimistic about the panel’s odds. “She is one of the best legislators I’ve ever dealt with, and she’s got two veterans with her who are terrific.”

As he has done in recent in weeks, Reid also took aim at Americans for Tax Reform President Grover Norquist, the influential conservative activist whose anti-tax pledge has been signed by the overwhelming majority of congressional Republicans.

“The difficulty we find is that in every one of these discussions, Grover Norquist seems to be in the room,” Reid said. “And as he indicated last night, he is quite sure that there will be nothing done with tax revenues. That’s Grover Norquist, who seems to be elbowing his way into all these rooms where we’re having these meetings.”

Senate Minority Leader Mitch McConnell (R-Ky.) said Tuesday afternoon that he believes the Republicans on the committee are “working diligently to get to a solution.”

“We think the country, the markets and the world need to see the American government succeed,” he said.

McConnell also took aim at Schumer, arguing that when the No. 3 Democrat speaks, “he’s speaking for the most partisan Democratic position.”

“It does raise your suspicion that the folks down at the White House are pulling for failure, because, you see, if the joint committee succeeds, it steps on the story line that they’ve been peddling, which is that you can’t do anything with the Republicans in Congress,” McConnell said.