A group advocating for a flat sales tax is going up with a new nationwide ad buy urging members of Congress to abolish the IRS.

Americans for Fair Taxation, a group headed by wealthy super PAC donor Leo Linbeck III, will launch the ads Monday. The ad buy is in the mid-six-figures, according to the group.

"Our best chance ever to shutter the IRS is now," the ad concludes, urging people to visit the EndtheIRS.com Web site and call an 800 number to join the effort.

Americans for Fair Taxation is a group devoted to enacting the Fair Tax -- a measure that would replace the current tax code with a flat, 23 percent sales tax. The ad campaign, though, doesn't push for a specific solution once the IRS is abolished.

Linbeck made a splash in the 2012 election by founding a super PAC devoted to unseating incumbents in primaries, called the Campaign for Primary Accountability.

That group will consider a lawmaker's stance on abolishing the IRS as part of its criteria for determining whether to fund primary challenges against them.