In what tea party groups are calling a "battle to save America from the Obamacare 'train wreck,'" Republican lawmakers plan to appear at a Capitol Hill rally on Sept. 10 to promote a proposal to defund the Affordable Care Act.

Filibuster_Fight-0c916_image_982w Sen. Mike Lee (R-Utah) and Sen. Ted Cruz (R-Texas) (AP Photo/J. Scott Applewhite)

Republican senators Rand Paul (Ky.), Mike Lee (Utah) and Ted Cruz (Tex.) will headline the "Exempt America Tour" rally on the West Lawn as a culmination of a five-day tour of six states. The tour, which will kick off in Kentucky on Tuesday, is sponsored by seven tea party groups, including Tea Party Patriots and For America.

The tour is the latest effort to pressure Republican lawmakers to take a tougher stance against Obamacare. It comes after a pointed online ad campaign targeting GOP senators who either oppose defunding Obamacare or haven't yet announced a position. Republican leaders who have been the subject of online ads include House Speaker John Boehner (Ohio) and Sens. Lamar Alexander (Tenn.), Jeff Sessions (Ala.), Tim Scott (S.C.), Thad Cochran (Miss.), Pat Roberts (Kan.) and Patrick J. Toomey (Pa.).

“If these Washington politicians think they can simply go home on summer break and claim they are doing everything they can to get rid of ObamaCare they have another thing coming,” said For America Chairman Brent Bozell in a statement.

Though it's been more than three years since the Affordable Care Act was signed into law and over a year since it was upheld by the U.S. Supreme Court, opposition to the measure lives on.

While some Republican lawmakers question the strategy of defunding Obamacare now (it's slated to go into affect on Oct. 1), tea party organizers remain steadfast.

"This is the last chance to stop ObamaCare before its massive subsidies and regulations go into effect January 1. Democrats have brought about this disastrous law, but it is Republicans who must unite to stop it and force Democrats to either defend the law or hold off funding," Bozell's statement said.