Updated 2:43 p.m. ET, 8/19
Washington (CNN) - Conservatives backing the push to shut down the federal government if funding isn't cut off by the end of September for President Barack Obama's health care law are launching new ads and a series of town halls starting this week.
The new drive comes as a growing number of Republicans are resisting such calls for a government shutdown over the Affordable Care Act, better known as Obamacare.
Heritage Action for America, a leading political advocacy group, Monday announced it would spend more than half a million dollars to run on-line ads in the districts of 100 House Republican lawmakers who have not joined the drive to try and defund the healthcare law. Last month Heritage Action joined 49 other conservative groups in demanding the House GOP leadership pass a bill to fund the government but not allow any money for Obamacare.
"The American people may have been locked out of the legislative process that gave us Obamacare, but they will be the force behind stopping this unworkable, unaffordable law. Congress should seize the moment and defund the entire law," said Heritage Action CEO Michael A. Needham, in a statement.
The announcement by Heritage Action comes on the same day that two other conservative groups, ForAmerica and Tea Party Patriots, also launched an on-line ad campaign targeting GOP senators and House Speaker John Boehner in an effort to persuade them to defund ObamaCare.
Some conservative lawmakers, including Senators Ted Cruz of Texas, Marco Rubio of Florida and Mike Lee of Utah, are using upcoming budget battles as leverage, vowing to oppose any measure that provides funding for the federal government that includes funding for the health care law. The measure funding the federal government expires September 30, setting up another Capitol Hill budget battle between congressional Republicans and the White House.
But so far only slightly more than a dozen fellow Republican senators have signed up to support the cause, leaving it up to outside conservative groups to rally the base.
The announcement of internet ads by Heritage Action, which is a sister organization of the Heritage Foundation, one of the oldest and largest conservative think tanks, comes on the same day the group is launching a nine-stop "Defund Obamacare Tour." Joining the series of townhalls, which kick off Monday in Fayetteville, Arkansas, are former Sen. Jim DeMint, the Heritage Foundation president, and Rafael Cruz, the father of Sen. Cruz. The senator from Texas will join DeMint and his father at the second town hall, Tuesday in Dallas.
Two progressive groups, Americans United for Change and Protect Your Care, plan counter protests outside the townhalls.
"Pro Health Reform advocates are going to meet the repealers and defunders on the battlefield and confront them directly and aggressively," says Brad Woodhouse, president of Americans United for Change. "A strong majority of the American people want the Affordable Care Act implemented and fixed if necessary – they do not want it repealed – which is the only plan for health care Republicans have."
Americans appear divided on whether they want the law, which passed in 2010 along party lines when the Democrats controlled both houses of Congress. In one of the most recent surveys on the law, conducted last month for CBS News, nearly four in ten called for the entire law to be repealed, with 18% saying that just the measure's controversial individual mandate should be repealed. Thirty-six percent of those questioned said that the law should be kept as is, or expanded.