As the campaign season for the 2014 midterm elections approaches, conservative activists are targeting vulnerable Democrats over their support for ObamaCare, signaling that the president's signature health care law will play a key role in yet another election cycle.

Americans for Prosperity, a conservative political advocacy group that focuses on economic policy, is spending $600,000 on TV spots targeting Reps. Rick Nolan, D-Minn., and Ann McLane Kuster, D-N.H., as part of a broader $16 million ad campaign, The Hill reported.

The ad against Nolan focuses on health plans canceled as a result of ObamaCare and features Randy Westby, a Minnesota resident who criticized Nolan for supporting the law.

"I received notice that my current insurance was no longer qualified. I've had three heart attacks in the last six years. Healthcare is something that's essential. My life depends on it," Westby says in the ad. "Congressman Nolan, ObamaCare needs to be repealed. It was a big lie."

President Obama had long promised that people who liked their policies could keep them. But many consumers recieved notification from their insurers in October and November that their individual policies would be canceled because they didn't cover benefits required by the law.

The Obama administration announced Nov. 14 that companies could continue existing policies that don't meet the minimum requirements if state regulators approved.

The National Republican Congressional Committee released a similar radio ad earlier this month targeting Rep. Carol Shea-Porter, D-N.H., who voted against a measure to repeal the law in May. The ad features a woman describing her husband's health problems.

“Because of ObamaCare, our health plan no longer exists, and our new policy doesn't cover the hospital where my husband was being treated,” the woman says. "Different hospitals, different doctors, during all this. I'm scared for him, and for the kids."

In a number of Senate primary campaigns, Republicans are arguing among themselves over the best way to oppose the law. The outcome of those campaigns could influence which party controls the Senate.

In Tennessee, state Rep. Joe Carr blasted Sen. Lamar Alexander for serving as a key GOP negotiator in the deal to end the partial government shutdown that resulted from House Republicans' efforts to deny funding for the health care law. Alexander subsequently described himself as a "conservative problem solver," a characterization that Carr says "typifies how out of touch he is."

Kentucky businessman Matt Bevin is using a similar line of attack in trying to unseat Senate Minority Leader Mitch McConnell, as is Mississippi state Sen. Chris McDaniel in his primary challenge to Sen. Thad Cochran. Carr, Bevin and McDaniel all say they'd be more like freshmen Sens. Mike Lee of Utah and Ted Cruz of Texas, tea party favorites who pushed the defunding strategy and vexed their longer-serving colleagues.

Leaders of national conservative groups, which have been key players in recent Senate elections, say the distinction is an important consideration as they decide endorsements.

The recent record of groups like Freedomworks and the Senate Conservatives Fund is mixed. Democrats are hoping for a repeat of 2010 and 2012 races where the far right groups backed less-viable candidates who lost general elections in Colorado, Nevada, Delaware and Indiana.

But the same groups also helped elect Lee, Cruz and Marco Rubio in the presidential swing state of Florida. At FreedomWorks, PAC treasurer and policy chief Dean Clancy dismissed any notion that wading into intraparty skirmishes would hurt the GOP.

"Republicans make a mistake when they try to waffle on these issues or sound like Democrat-lite," he said.

The Associated Press contributed to this report.