Senate Majority Whip Dick Durbin keeps getting knocked down, but he’s not giving up on his quest for a big bipartisan budget deal.

The liberal Illinois Democrat is an unlikely deficit hawk, but he continues to plug away in the thankless job of hammering out a grand compromise with Republicans — despite fire from his party’s base and occasional pushback from his own leaders, including Senate Majority Leader Harry Reid (D-Nev.).

“There just hasn’t been a buy-in at the leadership levels,” Durbin lamented in an interview this week. “That’s what we need.”

Durbin’s own journey as liberal party leader to a leading deficit reduction advocate in the bipartisan “gang of six” came a bit by accident.

“I didn’t do this with any grand design,” he said.

Durbin was one of Reid’s picks for the Bowles-Simpson fiscal commission set up by the president last year, and despite his reservations about potential cuts to social safety-net programs that Democrats hold dear, he became a key supporter of the commission’s plan.

He said that while he was on the panel, he came to understand the depth of the nation’s fiscal problems and that something serious has to happen to address the country’s financial problems. And perhaps more than any other liberal, he has made the case that cutting the deficit is critical to saving programs they hold dear.

“If we just say we can spend our way out of this, tax our way out of this, ignore the long-term impact, I think we don’t have a credible position in the year 2011,” Durbin said.

With Senate Democratic Policy and Communications Center Chairman Charles Schumer (N.Y.) assuming the role of the party’s messaging chief after the 2010 elections and Conference Secretary Patty Murray (Wash.) helming the Democratic Senatorial Campaign Committee and the new Joint Committee on Deficit Reduction, Durbin has been perhaps less visible but has thrown himself into a host of policy issues and found a place for himself in bridging the gaps of a deeply divided Senate.

“This is a balancing act,” he said of his dual roles as Whip — the party enforcer — and as someone pushing a compromise with the GOP. “Leadership gives you an opportunity to sit in the room and really debate the issues and strategy, and I’m honored and grateful to be there,” Durbin said.

“I’m also the Senator from Illinois and a Senator in 2011 with a friend as president, and we’re facing an economic challenge the likes of which we’ve never seen,” Durbin continued. “I’m trying to make sure these things are in balance, and I think I’ve done it so far.”

He said that he’s kept Reid informed about his legislative activities so that there would be no surprises. But when months of often tedious work in the gang of six finally yielded a deal in July, leaders in both parties, including Reid, dismissed the compromise and said a deal would have to come from the White-House-led talks.

Durbin did not fault Reid for withholding his support from the gang of six or from other bipartisan efforts. Reid, the Whip said, “thinks in terms of moving the caucus,” and Durbin said there are a dozen or so Democrats who will never support the sort of sweeping plan advocated by the gang of six. Senate Minority Leader Mitch McConnell (R-Ky.) has a similar problem on his side of the aisle, and Durbin said that without Reid and McConnell’s support, it would be difficult for any bipartisan deal to catch on.

“Will the day come when we become viable?” Durbin mused of the gang of six  efforts. He thinks the answer could be yes, perhaps in the super committee.

“We want to put our proposal on the table as something for them to consider, and I hope they will, and I think we can help them,” Durbin said, noting the backing from more than three dozen Senators last week for the super committee to shoot for a large deal. “There’s nothing else — nothing else — that has this measure of bipartisan support on the Senate side.”

And “if they are not successful, this could turn out to be an alternative approach,” he added.

Durbin, however, would rather be on the committee than a cheerleader.

“I wish I were there,” he said. “I think I could have added something.”

But Reid consciously passed over him and the other gang of six members for his picks, as did McConnell.

Despite his disappointment, Durbin said of Murray: “We all think the world of Patty,” who serves as super committee co-chairwoman.

Reid told Durbin he thought it was important to appoint a woman to the panel, and Durbin agreed. As for his other picks, Reid “was just writhing in political pain,” Durbin said, adding that he wouldn’t second-guess Reid’s decision to name Murray, Senate Finance Chairman Max Baucus (Mont.) and Sen. John Kerry (Mass.) to be the Senate Democrats’ committee representatives.

Similar to Reid’s need to make political calculations before embracing any major bipartisan deficit reduction package, Durbin said the president was in a tough spot after his deficit commission recommended raising the retirement age under Social Security and eliminating popular tax deductions.

Though Obama did not to publicly embrace the Bowles-Simpson plan, Durbin said the president had been supportive privately, at least in principle.

“I know that from personal conversations with him,” Durbin said. “We talked about it, and had he done that, it would have been the ‘Obama plan’ and there would have been a firestorm against it. He had to measure when he spoke and what he said on that basis.”

But Durbin noted that the president has on at least three occasions this year tried to negotiate with House Republicans, and each time, they have walked away from the talks. He criticized New York Times columnist David Brooks for questioning Obama’s move toward a more partisan deficit plan this week: “I’ll tell you why David, because three times now he stuck his neck out, and what happened? Nothing.”

Still, being passed over for the super committee and having the gang of six plan dismissed by Reid has raised questions about Durbin’s role within Democratic leadership. By all accounts, he’s a “hero” to moderates, such as Budget Chairman Kent Conrad (D-N.D.), and is trusted by many of the party’s liberals. But exactly where he fits in the broader picture remains an open question.

Durbin’s taken some criticism from his party’s base for his willingness to compromise, but the Senator said many of those groups privately will acknowledge something has to happen.

“When the doors close and you guys are gone, there’s a practical conversation,” Durbin told Roll Call.

Durbin said Democrats and liberals should look at the Bowles-Simpson and gang of six plans as not necessarily ideal but as proposals that preserve many of their priorities.

Durbin said he insisted the tax code had to be on the table and that final rates had to be at least as progressive as they are today. He also agreed to cuts to Social Security to ensure its long-term solvency — but he negotiated for an increase in payments to seniors with the lowest incomes.

“I can hold my head up with any group of progressives and tell them, ‘If you even acknowledge deficit reduction is necessary, at least concede that I have set a foundation, a progressive foundation, for doing it,’” Durbin said.