A few months ago, Sen. Michael Bennet’s staff staged what the Colorado Democrat calls an intervention.

He had survived a brutal campaign in 2010 to win his first full term. But after a year of deadlock and partisanship in the Senate, he was wondering whether it had been worth the struggle. “It was right after we managed to end our session with a two-month extension of the payroll tax,” Bennet told me Wednesday. “I got to a point where I was referring to this place as the Land of Flickering Lights, because the standard of success was we kept the lights on for another two months.”

So his aides sat their boss down for a stern talk. “My chief of staff said to me, ‘You know, it’s not okay to hate your job,’ ” Bennet recalled. “And he’s right. There’s no point in wallowing in self-pity. No one’s going to feel sorry for you.” And so Bennet rededicated himself to his package of reforms — none of which has much chance of passing — and stopped the kvetching. “I’m back from the brink,” he said.

For now. But with each day on Capitol Hill comes more evidence that the place is broken beyond repair — and that the last remaining vestiges of sense and moderation are fleeing. The latest blow came on Tuesday, when Sen. Olympia Snowe of Maine, one of the Republican Party’s last moderates, said she wouldn’t seek a fourth term because she sees no imminent change in “the partisanship of recent years.”

Also heading for the door is much of the remaining core of Senate moderates: Republican Kay Bailey Hutchison of Texas; independent Joe Lieberman of Connecticut; and Democrats Kent Conrad of North Dakota, Ben Nelson of Nebraska and Jim Webb of Virginia. After that kind of exodus, Bennet will be one of the last reasonable lawmakers still standing. “I think that it should be a real wake-up call to people here,” he said. “There are a number of folks who don’t want to come here and participate in the dysfunction.”

Bennet is holding on in hopes that external events will eventually conspire to force action on a major federal debt agreement along the lines proposed by the Bowles-Simpson commission, but he acknowledges that it won’t happen this year. In the meantime, he’s keeping his sanity by focusing on relatively small stuff.

Wednesday morning found Bennet at the conservative American Enterprise Institute, pitching his idea for improving education with technology. The $90 million proposal is small change, but Bennet spoke with passion about how it could “give us the chance to create the most major advance in K-12 education since Colonial America.”

Bennet, with his wrinkled suit pants, frayed collar and tendency to rub his nose while he gives a speech, is an accidental politician: He was the superintendent of Denver schools before being appointed to fill a Senate vacancy. This makes him exactly the person who should be revising federal education policy. “In view of the fact that there isn’t anything more important than education to drive the U.S. economy, it’s amazing to me how little attention is spent on it,” he told the AEI audience, ignoring his creased notes.

On the campaign trail this year, the talk has been about birth control and theology and Rick Santorum’s view that President Obama is a “snob” for wanting Americans to go to college. Bennet, who uses phrases such as “fatigue with longitudinal data,” has what he calls a “snobby” rejoinder to that way of thinking: During the recession, the unemployment rate for people college degrees never exceeded 5 percent.

When he’s not getting wonky with education scholars, he’s working on reducing the use of the filibuster in the Senate, imposing on Congress members a lifetime ban from lobbying, and requiring more campaign-finance disclosure. Prospects for the three range from unlikely to doomed, but the 47-year-old lawmaker continues to tinker: with FDA reforms, wind-power incentives and “teacher residency” programs.

So far this year, his despair hasn’t returned. “You’ve got to get up every morning and just try to figure out how to make a contribution,” he said. “At some point, we’ll have to respond to our constituents’ desire that we knock it off. At some point, we’ll head in that direction, but Washington seems to have an antibody in it right now that is fighting this at every turn.”

Let’s hope that changes before the last few Michael Bennets go the way of Olympia Snowe.