A pair of tea party groups is teaming up to pressure key Republicans to support an effort to defund Obamacare.

Tea Party Patriots and the grassroots group For America are launching online ads against a dozen GOP senators who either oppose the effort or haven't announced a position.

Along with the ads, leaders of the groups will embark on a six-state, five-day "Exempt America" tour (the idea being that the American people should be exempt from Obamacare) that will bring them to the home states of several of these senators.

Update 12:01 p.m.: The conservative group Heritage Action is also launching an online ad campaign pushing the Defund Obamacare effort. Heritage will spend $550,000 on online ads targeting 100 House Republicans.

The effort comes as Defund Obamacare -- whose supporters pledge not to fund the government if it includes money for the president's health-care law -- struggles to gain the traction it would need to actually force the issue. Several GOP senators have opposed the strategy in no uncertain terms.

Through the online ads and the multi-state tour, Tea Party Patriots and For America will accuse such senators of supporting the law if they vote for a budget or a continuing resolution that includes money for Obamacare.

The first wave of ads will target six Republicans who have expressed skepticism about the Defund Obamacare effort: Senate Minority Whip John Cornyn (Tex.) and Sens. Lindsey O. Graham (R-S.C.), Mark Kirk (Ill.), Kelly Ayotte (N.H.), Tom Coburn (Okla) and Richard Burr (N.C.).

These ads will mirror For America's recent "chicken" ad targeting Senate Minority Leader Mitch McConnell (R-Ky.). The spot uses quotes from the senator, suggests that he shouldn't be a "chicken" and concludes by saying, "You fund it. You own it."

Here is the online ad that will run against Graham:

The second wave of ads will target six Senate Republicans who haven't made their positions clear, calling on them to exercise leadership on the issue. The six are Sens. Lamar Alexander (Tenn.), Jeff Sessions (Ala.), Tim Scott (S.C.), Thad Cochran (Miss.), Pat Roberts (Kan.) and Patrick J. Toomey (Pa.).

A similar ad will target House Speaker John A. Boehner (Ohio).

The six-state tour will complement the ads and will travel through many of these members' home states -- including Boehner's.

Tea Party Patriots co-founder Jenny Beth Martin and For America Chairman Brent Bozell will team up to travel to Boehner's home state of Ohio and McConnell's Kentucky before moving on to Texas, Mississippi, South Carolina and Virginia.

The Defund Obamacare movement is being led in the Senate by Sens. Mike Lee (Utah) and Ted Cruz (R-Tex.), with Sens. Marco Rubio (Fla.) and Rand Paul (Ky.) also signed on to the effort.

Other Republicans, though, have balked at the tactic and have said it's not a practical way to get rid of the president's health-care law. They also worry that it would be politically risky to threaten to shut down the government if Obamacare isn't defunded.

Burr, for example, called it the "dumbest idea I've ever heard," and Coburn labeled it a "failed strategy."

Cruz told the Daily Caller last week, "If Republicans are truly against Obamacare, they will not vote to fund it."