Here are some of the phrases people have used to describe Democratic Senator Russ Feingold: “A humorless scold.” “Insolent, arrogant, aloof.” “A holier-than-thou prig.” And it’s not terribly surprising. Feingold has made a habit of annoying his colleagues, like the time in October, 2001, when he introduced a bill to freeze congressional pay and end automatic cost-of-living increases. “I’m pretty sure I wouldn’t win a Mr. Popularity contest,” Feingold told a reporter many years ago. “I have no illusions about that.”

Once upon a time, Feingold's unpopularity in Washington translated into popularity where it mattered most: His home state of Wisconsin, which three times elected him senator. It was a perfect match--the quirky, unpredictably progressive senator in the quirky, unpredictably progressive state.

But Feingold is struggling this election season. Polls show him trailing plastics magnate Ron Johnson. Although Feingold has been campaigning furiously, and although a recent survey put Feingold within the margin of error, most of Washington expects him to lose. If so, it would be a great loss--and not merely in the sense that Republicans would be one Senate vote closer to enacting an agenda a lot of people (myself included) find dangerous.

As a general rule, I think, the media and the public put too high a premium on political independence. Politicians who loudly defy their parties win adulation, even when they are grandstanding, while officials that work within the system, earnestly trying to make the country a better place, get ignored. 

But independence isn’t a pose for Feingold. And it has led him to take a series of genuinely brave positions over the years. He was the lone dissenter against the Patriot Act and a loud, early critic of the Iraq War--warning, presciently, that it would distract the government from much more serious threats elsewhere. (Of particular relevance today: As early as 2002, he wanted to know why American counter-terrorism officials weren’t focusing more on the danger from Yemen.) Feingold’s dedication to the idea of clean elections led him to co-sponsor the McCain-Feingold Act, arguably the most important piece of campaign finance legislation since the late 1970s--at least until the Supreme Court unraveled it.

Of course, Feingold is also a true liberal. The votes he cast over the past two years--for the stimulus, raising the debt ceiling, and particularly health care reform--have become major liabilities. As Ben Smith notes in Politico, Feingold’s opponent, plastics magnate Ron Johnson, has attacked Feingold repeatedly over these stands. Maybe Feingold was independent before, Johnson suggests. But he’s not anymore.

Johnson's attacks work in part because they distract from his own underwhelming qualifications for office. His inability to provide even the sketchiest of details about his ideas for the economy led even the Green Bay Press-Gazette, one of the state's most conservative papers, to endorse Feingold. ("Johnson seemed unable to further articulate his plan for job creation--especially for the middle class--during a recent meeting with the Green Bay Press-Gazette editorial board," the paper wrote, adding "he needs more time to develop and articulate his positions on a range of issues from jobs to foreign policy.") 

Ironically, a big factor in Feingold's struggles may be the stubborn independence he's supposedly lost. Consistent with his longtime opposition to unlimited campaign spending by outside groups, Feingold has told organizations that support him, including the Democratic Senatorial Senate Committee, to stay away from his race. The Sunlight Foundation has calculated that outside groups have spent around $2.7 million on advertisements in the Wisconsin Senate campaign. Of that, $2.67 million have been on ads against Feingold or for Johnson.

Feingold's prohibition on outside money is a form of unilateral disarmament. And it's emblematic of an approach to politics that infuriates some of his allies in Washington. As one liberal lobbyist told me recently,

What pisses me off is that he refuses to do any "negative" campaign ads. So he hasn't pointed out how extreme Johnson is--especially for Wisconsin. You look at the other senators in trouble: Reid, Boxer, Bennett. They hammered their opponents and they are in better position than Feingold, although they are all at risk of losing as well.

But this lobbyist added something else:

He is definitely one of the few senators, on either side of the aisle, who really sticks to his principles. That's a rarity indeed.

I think that sums up Feingold pretty well. He can be a real pain in the ass. And if he's gone from the Senate, we'll be worse off for it.