Cato Institute scholars are not exactly thrilled that liberal activists are siding with them in their battle against Charles and David Koch.

Even as the libertarian think tank works furiously to round up a coalition to help it fight a lawsuit filed by the billionaire brothers that would vastly expand their control over the organization, campaign finance reformers are not particularly welcome.

United Republic, a group launched last fall to fight corporate money in politics, organized a rally outside Koch Industries’ Washington, D.C., headquarters Tuesday to protest the Kochs’ attempted takeover. The group’s activists were joined by others from Common Cause, another campaign finance watchdog group with liberal tendencies.

“Thanks, but no thanks,” said Jerry Taylor, a senior fellow who has worked at Cato for 21 years. “We don’t have any complaints with money in politics; we think the more money in politics the better. … I’m sure a lot of people and a lot of interest groups will be tempted to use this struggle to advance their agendas.”

Cato is locked in a legal battle with one of its founders, Charles Koch, the billionaire conservative known for backing a powerful network of Republican political organizations, including Americans for Prosperity and FreedomWorks. The Kochs are asking a Kansas court to enforce an old agreement that would give the brothers an opportunity to control the four-person shareholder group that governs the institute as well as the authority to appoint a majority of a separate 16-member board.

Cato scholars say the move would sully the reputation of the highly respected research organization.

United Republic, one of several new Occupy Wall Street-inspired advocacy groups that popped up late last year, sees it as another opportunity to champion its cause.

The group describes itself as nonpartisan, but at least three of its senior staffers are veterans of the liberal Center for American Progress. That includes David Halperin, the think tank’s former senior vice president and the senior policy adviser for Howard Dean’s 2004 presidential campaign.

United Republic’s president, Nick Penniman, is the former associate editor of the liberal magazine American Prospect, and Tom Fazzini, the organization’s deputy communications director, worked on the 2008 Obama campaign between press jobs for Democratic Sens. Ben Nelson (Neb.) and Ron Wyden (Ore.).

Fazzini said Tuesday’s protest was part of an effort to appeal to players across the political spectrum. Fighting the influence of special interests has long been a Democratic trope, but tea party activists have shown interest, too.

“A think tank providing independent analysis is very different from a think tank that simply does something on behalf of a political party or a corporate donor,” said Zaid Jilani, communications and outreach director at United Republic. “We certainly have a disagreement with them about the role of money in politics … but I also have a number of friends at Cato who are privately supporting us.”

The demonstration — attended by no more than about 20 activists — attracted the attention of trackers from the Washington Free Beacon, a conservative media watchdog group launched last month to counter the left-leaning Media Matters for America.