Speaking on CNN's "State of the Union," Durbin, the majority whip, said the bipartisan group was near a deal when Coburn walked out.
"We put everything on the table, and we cut the deficit by more than $4 trillion over 10 years. We were ready to announce as far as I was concerned, and then Senator Coburn said no, I'm not part of this and then walked away," Durbin said.
He said the president's Simpson-Bowles Commission had provided "a great starting point."
"What we need this week is for a bipartisan group of senators to step up and tell us, now the Gang of Five, we want to sit down with you," Durbin said.
"We should not abandon all the work we've put into it. It needs to be a bipartisan starting point, and we are making that offer to both caucuses.
"We need some Republican buy-in in this," he added.
Durbin also warned against letting the government default by not raising the debt ceiling.