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.

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.