This story has been updated.

The No. 2 Senate Democrat on Wednesday called it a “breakthrough” that the debt supercommittee’s Republicans mentioned the word “revenue” in their most recent offer, even as other senior Democrats are panning the proposal.

“I assume good faith,” Sen. Dick Durbin (D-Ill.) told reporters at the Capitol Wednesday morning. “I think that’s the best starting point. And I assume that what we heard from Republicans is a breakthrough that can lead to an agreement, and that’s what we need.”

Most Democrats on Tuesday publicly derided the offer presented by the supercommittee’s Republicans at a late Monday night huddle. They argue that the plan – which Republicans say would raise federal tax revenue by as much as $300 billion over the next decade – was hardly a concession on the GOP’s anti-tax stance.

Sen. John Kerry (D-Mass.), one of three Senate Democrats on the bipartisan panel, told reporters Tuesday that the move was only a “slight” change from Republicans’ earlier position. And Sen. Patty Murray (D-Wash.), co-chair of the debt supercommittee, said that she has “yet to see a real, credible plan that raises revenue in a significant way to bring us to a fair, balanced proposal.”

But Durbin, who has also been a member of the bipartisan “Gang of Six” senators engaged in talks earlier this year at reaching a far-reaching debt-reduction deal, that he believes Republicans’ latest proposal represents an honest effort and a shift in the debt-reduction talks simply because “the word ‘revenue’” has entered the conversation.

“It is a breakthrough,” he said. “I think you have to be honest. There haven’t been many who have stepped forward, except in our group [the Gang of Six], you know. They’ve been pretty forthright in our group. But the group appointed to the subcommittee, this is the first time – at least publicly – that we know that it’s on the table.”

Durbin’s remarks come as Senate Majority Leader Harry Reid (D-Nev.) and Minority Leader Mitch McConnell (R-Ky.) have escalated the war of words over the supercommittee in anticipation of a potential failure by the panel, which is facing a deadline two weeks from now.

Reid at his weekly news conference Tuesday charged that Republicans on the committee are continuing to balk at new tax revenue out of fear of retribution by anti-tax activist Grover Norquist. McConnell shot back that the White House is “pulling for failure” in order to make it easier for President Obama to run against a “do-nothing Congress” in 2012.

Durbin said Wednesday that “to argue that [Obama] is not in favor of meaningful deficit reduction runs counter to the evidence,” noting that Obama signed the debt-ceiling bill that created the supercommittee, endorsed the Gang of Six proposal and “has tried on three separate occasions to reach a larger deficit-reduction plan.”

Asked whether Obama should be more personally involved in the committee’s work, Durbin described the situation as a lose-lose one for the president.

“Let me tell you, he’s damned if he does, and he’s damned if he doesn’t,” Durbin said. “If he gets involved, it becomes the ‘Obama Budget Plan,’ and people say, ‘That’s it, I’m walking out.’ If he doesn’t get involved, they fault him and say, ‘You know, he really knows how to get this done, and he just doesn’t engage.’ But I think he’s trying to strike the right balance.”

“At this point, it’s in our hands on Capitol Hill,” he added.

Durbin also told reporters that on Tuesday, a bipartisan group of 30 of the 45 senators who backed the Gang of Six effort met to discuss their support of the supercommittee. The lawmakers are planning to make a brief statement later Wednesday urging the supercommittee to reach an agreement that exceeds its $1.2 trillion mandate.

“I think bigger is easier,” Durbin said. “I really believe that when you’re dealing with a major change in the area of $4 trillion, that you can really start putting things on the table in an honest way that you can’t when you’re at the lower end of $1.2 or $1.5 [trillion].”

Among the 30 senators at Tuesday’s meeting were the three Republican members of the Gang of Six – Sens. Saxby Chambliss (Ga.), Tom Coburn (Okla.) and Mike Crapo (Idaho). All three signed onto a letter sent by 33 Republicans senators to the supercommittee last week urging “no net tax increase” in the panel’s final plan.

Asked Wednesday about the letter, Durbin said that he greeted it with a “momentary panic” but ultimately did not view it as an obstacle to a bipartisan debt-reduction deal because of the different language that Democrats and Republicans use in talking about each party’s sacred cow -- entitlement programs and taxes.

“After discussing it with those senators and other senators, I do not believe that it is going to be an obstruction to what we’ve set out to do as far as deficit reduction,” Durbin said of the letter.

“To put it in simplest terms, when we speak of entitlements, Democrats will describe it in a different way than Republicans. When we speak of revenues, the opposite is true. I want to give flexibility to my colleagues to find a good place to stand, and I want them to be able to stand for a bipartisan solution. I don’t think that letter is going to jeopardize that.”

Kerry on Wednesday renewed his criticism of the GOP plan, saying that the approach taken by Republicans in their latest proposal “will not work.”

“We have a big gap with respect to where we are,” Kerry said in a brief interview. “There’s an awful lot of good things we’re talking about. There’s a lot of progress on a lot of things. There’s a gap on that. ... We’ve told them that very directly. We have to find a different way to come at it.”

Staff writer Rosalind S. Helderman contributed to this story.