In the rough and tumble world of politics, it’s one thing to go after your opponent. It’s another to use your tax-exempt status and the government’s resources to vilify someone with scurrilous legal attacks during an election with the intent of sinking their campaign.

2010 Delaware Senate candidate Christine O’Donnell alleges that Citizens for Responsibility and Ethics in Washington is guilty of the latter. She says CREW filed a meritless complaint late in the election solely to harm her campaign. And she probably has a case.

Our extensive analysis of CREW’s official complaints, lawsuits and other official actions between its founding in 2003 and 2010 reveals that the group targets Republican politicians and right-of-center nonprofit organizations by a ratio of more than 8-to-1 compared with Democrats and liberal groups.

Government agencies, on the other hand, have found wrongdoing to have far more of an equal-opportunity record.

Specifically, CREW has filed more than a dozen complaints with the IRS regarding the behavior of nonprofit organizations and Members of Congress: 100 percent of those complaints were leveled at Republicans and right-leaning nonprofits. CREW has filed 29 complaints with the Federal Election Commission since 2004. Of those complaints, 76 percent were filed against Republicans and groups on the right, while 10 percent were filed against Democrats and groups on the left.

Since 1980, however, the number of civil penalties levied against Republicans of more than $50,000 by the FEC is only 40 percent, while the percentage of political or ideological organizations on the left and on the right that have been stripped of their 501(c)(3) status is equal.

From June 2003 to September 2010, CREW requested 67 investigations by the Department of Justice and other law-enforcing agencies. Of these requests, two-thirds targeted Republicans. Only 10 percent targeted Democrats (the remainder were either bipartisan or nonpartisan).

It is not surprising that this has raised the eyebrows of tax attorneys. Former IRS official Richard J. Wood was quoted in 2006 as saying that if someone were to complain about CREW’s actions “at least preliminarily, I think they have a good case.” He cited a memo from the IRS stating that organizations that show a “long-term strategy of engaging in prohibited behavior” can have it used against them.

While this might not be news to most Beltway denizens, outside of our little bubble, CREW is consistently cited as a source for ethical judgments, regularly described as a “bipartisan,” “nonpartisan” or a “watchdog” group by members of the press. Funded by wealthy Democrats and run by liberal activists, CREW is as partisan as it gets.

As someone who regularly tangles with Big Labor (a big funder of CREW) and proponents of the nanny state, I often find myself in CREW’s cross hairs. They are desperate to shut down the opposition.

When confronted by claims of partisanship, CREW Executive Director Melanie Sloan responds that the group is strictly nonpartisan. But when CREW targets Democrats, it’s typically long after other organizations or the mainstream media have already completed investigations and often involves taking little more action than drafting a press release. For instance, it was only after House Minority Leader Nancy Pelosi (D-Calif.) called for disgraced Rep. Anthony Weiner (D-N.Y.) to resign that CREW chimed in with a “me, too” call for his resignation.

It’s not surprising that CREW trains its sights on Republicans. It is, after all, the brainchild of prominent Democrats such as Norman Eisen (deputy general counsel to President-elect Barack Obama’s transition team in 2008) and Mark Penn (a longtime Democratic pollster and strategist with strong ties to the Clintons). The organization’s funding comes from groups with ties to George Soros, including the Open Society Institute and the Democracy Alliance.

Employees at CREW come from or go on to work at liberal outfits such as Media Matters for America and the American Civil Liberties Union — that is, when they don’t migrate directly from the offices of Democratic legislators. Indeed, an analysis of the publicly available information for those on CREW’s roster of employees shows that none of them have worked for a single Republican or right-leaning organization.

Sloan’s experience is typical. Before coming to CREW, she served as minority counsel for the House Judiciary Committee under Rep. John Conyers (D-Mich.). She also worked under Sen. Charles Schumer (D-N.Y.) when he was in the House and for then-Sen. Joseph Biden (D-Del.).

CREW might be many things, but it is far more of a Democratic lapdog than an unbiased watchdog.

Rick Berman is executive director of the Center for Consumer Freedom.