A conservative advocacy group is targeting Democratic U.S. Senate candidate Bruce Braley of Iowa with a new television ad that accuses him of lying about the Affordable Care Act and faults him for standing by the nearly 4-year-old law.

The ad, which is being paid for by Americans for Prosperity, is running statewide. It faults Braley, a congressman from Waterloo, over the claim that Americans who like their insurance plans can keep them. It also suggests the law is wreaking havoc in the state.

"Our plans cancelled, our doctors lost, our premiums skyrocketing," the ad's narrator says.

Republicans have said the health care law will be a large part of their agenda for the fall election.

Americans for Prosperity said the TV ads will be supported by radio and online advertising, too, along with a grassroots campaign.

"It's time for Rep. Braley to listen to Iowans and stop defending this terrible law," the group's Iowa director, Mark Lucas, said in a statement.

Braley's campaign responded by contending that Americans for Prosperity and its founders are not on the side of middle-class Iowans and that they oppose policies that help the middle class, such as raising the minimum wage and extending tax credits for renewable energy.

"The Koch brothers and their Tea Party allies are at it again with a torrent of misleading attack ads because they support policies that hurt Iowa's middle class," said Jeff Giertz, a Braley spokesman.

Americans for Prosperity was founded by billionaire industrialist David Koch. His brother also has ties to it.

Braley's camp also sought to tie Republican Iowa Gov. Terry Branstad to the new health care law. It noted that in his Condition of the State address to the Iowa Legislature on Tuesday, the governor "touted his work implementing the new health care law" by pointing to the bipartisan plan to extend Medicaid in the state.

The ad's emphasis on policy cancellation centers on an issue that has proven to be tricky for the health care law's supporters.

Some have argued that the cancelled policies were not worth much in the first place, but as individuals have told stories about how their cost to replace them has gone up, it has caused a political problem.

Last year, Braley joined about three dozen other House Democrats in backing a Republican bill to allow people whose existing policies were not grandfathered in by the law to keep them. It also would allow insurance companies to continue selling the policies.

Senate Democrats would not take up the measure, saying it would undermine the Affordable Care Act.

For the most part, Iowans in the individual health insurance market have not seen their plans cancelled yet, according to the state insurance division.

However, that may be coming. Hundreds of thousands of people in the state saw their plans extended last year by Wellmark Blue Cross and Blue Shield, Iowa's largest provider.

Those plans are due to expire later this year, setting up the prospect that a wave of cancellations could take place then.

Americans for Prosperity says it is spending $500,000 over three weeks on the ad campaign.

The New York Times reported that the group is spending $1.8 million on ads in Iowa, Michigan and Montana.