Dr. David Gill, the Bloomington Democrat who narrowly lost the Nov. 6 race for the 13th U.S. House District, joined Citizens for Responsibility and Ethics in Washington, of Washington, D.C., in filing a federal lawsuit against the Internal Revenue Service.

The lawsuit's aim: to close a loophole that allows outside groups set up for charitable purposes to spend unlimited sums of money into political races.

The lawsuit, filed in federal court in Washington, D.C., accuses the IRS of flouting a federal law that bars certain nonprofit groups from engaging in political activity.

U.S. Rep. Rodney Davis, R-Taylorville, won the Nov. 6 election against Gill by less than 1 percent of the vote.

The lawsuit is asking a federal judge to order the IRS to enforce a federal law that requires 501 (c)(4) organizations, which are set up to promote social welfare, to refrain from political activity.

The lawsuit accuses the American Action Network, a top Republican 501 (c)(4) group, of deviating from its social welfare duty and, instead, paying for false and misleading negative campaign ads and robo-calls against Gill. The network reported spending nearly $1.5 million against Gill, according to the lawsuit.

Gill, during a teleconference Tuesday with leaders of the ethics group, accused the conservative-leaning American Action Network of running ads and robo-calls that falsely claimed he wants to demolish Medicare, when in fact he supports the strengthening of the federally funded health insurance program for the elderly.

Gill noted that he lost to Davis by 1,002 votes.

The $1.5 million the action network spent on negative advertising "touched a lot of people with a lot of false claims about me," Gill said. "I think that played a very important role in my defeat."

A representative from the American Action Network could not be reached for comment. A spokesman for Davis declined to comment.

Under a 2010 U.S. Supreme Court decision, outside groups, such as the American Action Network, may pour unlimited amounts of money into political races as long as they do not coordinate their efforts with the candidates running for office.

Outside political groups in 2012 spent nearly $7 million on the 13th U.S. House race -- almost all of that money paying for negative TV ads against candidates those groups sought to defeat.

The action network received big financial contributions from both insurance giant Aetna and the Pharmaceutical Research and Manufacturers of America, both of which oppose the single-payer, national health care plan supported by Gill, an emergency room physician.

The 13th U.S. House District covers parts of Madison County, and includes Collinsville, Maryville and Edwardsville, runs eastward to Champaign County, and covers 13 other counties.

Contact reporter Mike Fitzgerald at mfitzgerald@bnd.com or 618-239-2533.