About six months after the process began, the Gang of Six was reportedly close to presenting a bipartisan debt-reduction plan. By all accounts, the “compromise” was going to be titled heavily in conservatives’ direction — which is what happens when conservatives have a three-to-one advantage over liberals on a panel.

As of yesterday, however, the right-leaning deal wasn’t quite appealing enough for one of the Gang’s leading members. Sen. Tom Coburn (R-Okla.) announced he’s walking away from the talks. “We’re at an impasse,” Coburn told reporters. “There’s no reason to sit and talk about the same things over and over and not get any movement…. They don’t want to go where I want to go and I don’t want to go where they want to go.”

So, what happened? NBC News reported that Coburn “brought new issues to the table at the last minute that prevented the group from coming to a deal and gave the members the indication he was not negotiating in good faith.” The Washington Post‘s report noted the same thing.

Those close to the talks said trouble has been brewing for weeks. Earlier this month, the group appeared to be tantalizingly close to an agreement. But then, Democratic sources said, Coburn started bringing up new issues at every meeting, or demanding that old ones be reconsidered.

For example, Coburn began pressing for sharper cuts to Social Security than had been previously agreed to, according to sources familiar with the talks who spoke on the condition of anonymity because of the private nature of the negotiations. And during a three-hour session late Monday, the sources said, Coburn demanded deep and immediate cuts to Medicare that went beyond anything previously proposed.

Striking deals with those who constantly move goalposts is inherently tricky.

It’s probably too soon to say the Gang’s efforts are completely dead, since the five remaining members met yesterday after Coburn’s withdrawal and are scheduled to talk again today. But Coburn’s departure — and his unique credibility among conservatives — suggests the Gang is on the verge of collapse.

And for what it’s worth, that’s just fine with me. There was never any reason to believe the Gang’s deal could pass the House or Senate, and based on comments from participants, it was going to be a bad deal anyway.

As for bipartisan talks, it’s also worth remembering that the Gang wasn’t the only game in town. As Senate Minority Leader Mitch McConnell (R-Ky.) noted last week, “With all due respect to the Gang of Six, or any other bipartisan discussions going on on this issue, the discussions that can lead to a result between now and August are the — are the talks being led by Vice President Biden.”

Steve Benen

Follow Steve on Twitter @stevebenen. Steve Benen is a producer at MSNBC's The Rachel Maddow Show. He was the principal contributor to the Washington Monthly's Political Animal blog from August 2008 until January 2012.