WASHINGTON — Health insurers flirted with Democrats, supported them with money and got what they wanted: a federal mandate that most Americans carry health care coverage. Now they’re backing Republicans, hoping a GOP Congress will mean friendlier regulations.

They may get more than they’re wishing for.

The so-called individual mandate has provoked tea party conservatives, who see it as an example of big government interference in personal decisions. Now Republican candidates are running on platforms that include repealing the broader health care law. And attorneys general from some 20 states — mainly Republicans — are challenging the mandate as unconstitutional.

“If you ended up repealing that one provision, the whole thing blows up,” said Bill Hoagland, the top lobbyist for Cigna Corp. “It doesn’t work. The cost would explode.”

Still, Cigna, which early last year had been funneling money to Democrats from its political action committee, has shifted from a 50-50 split between the parties to around 70-30 in favor of Republican candidates.

Likewise, about $6 of $10 that Blue Cross Blue Shield Association’s PAC doled out from February through June 2009 went to Democrats. By last month, the ratio had shifted — Democrats got only about 35 percent of the insurer’s PAC money.

In all, from January through August of 2009, the health insurance industry donated $2.15 million to Democrats and $1.7 million to Republicans, according to monthly figures compiled by the Center for Responsive Politics. Since September of 2009, the industry has donated $2.4 million to Democrats and nearly $3.3 million to Republicans.

The GOP advantage has grown even as Republican candidates call for outright repeal of the health care law.

“This is really an incredible irony,” said Robert Laszewski, a former insurance executive turned consultant. “The insurance industry could be fighting with its traditional ally, the Republicans, not to cripple the bill, not to put a bomb inside the thing.”

Meanwhile, an Associated Press-GfK poll finds likely voters in the upcoming elections evenly split on whether the law should be scrapped or whether Congress should undertake even bigger changes in the way Americans get their health care. Thirty-seven percent said they want to repeal it. But 36 percent of those polled said they want to revise the law so it does more to change the health care system. Ten percent wanted modifications to narrow the scope of the overhaul. Only 15 percent said they would leave it as it is.

Though the insurers won the insurance mandate they wanted from President Barack Obama and the Democrats, they opposed the overall bill and now say they want to be sure the regulations they face aren’t onerous. A Republican-controlled Congress might accomplish that by pressuring the Health and Human Services Department through its control of the department’s budget or by subjecting regulators to congressional hearings.

A central worry for insurers is a planned requirement that companies spend a minimum 80 percent of premiums on medical care or rebate the difference to policy holders. They also want a say in defining what would be considered “excessive” premium increases that could expose an insurance company to sanctions.

“What they are looking for is someone who is going to be more sympathetic and supportive on the policy side,” said Peter Harbage, a Democratic health policy consultant.

There’s more to the shift in political support than a recognition that Republicans are within reach of regaining power. It’s also personal.

Some industry officials say they were stung by the fierceness of Democratic efforts to paint them as corporate villains in the debate over the new health care law. Liberals blamed insurers for forcing Obama to back away from a plan for optional publicly financed insurance for people who could not afford traditional coverage.

Then Obama, seeking to rally support for his plan, went on the offensive. Without an overhaul, he wrote in August 2009, “insurance companies will continue to profit by discriminating against sick people.”

From then on, political giving by the insurers flipped.

Democrats made it sound like insurance companies were “the scum of the earth,” Hoagland said. “That kind of pricked me.”

“We are not the ones totally responsible for all the failings of the health care system,” he said. “It persuaded me that we were not getting a fair shake.”

The attention to regulation is also playing out at the state level, where insurance regulators hold significant sway. Between 2005 and 2008, health insurance companies and health maintenance organizations contributed more than $32 million to state office holders, political parties and ballot measure committees, according to the National Institute on Money in State Politics. The top four insurers — WellPoint, UnitedHealth Group, Humana and Aetna — gave a quarter of that amount.

So far this year, based on available reports, those four firms have given $2.2 million to state candidates or parties, with Republicans getting more than half, Democrats about 40 percent and the rest to ballot initiatives, according to an institute analysis for The Associated Press.

The industry is keeping a wary eye on the law’s requirement that states create exchanges where insurers will compete to sell policies to consumers beginning in 2014.

“If your premiums go up too quickly, then you’re going to be excluded from the exchange,” Harbage said. “Every state is going to be responsible for collecting that data, looking at that data, interpreting it and making some kind of recommendation to HHS.”

At the national level, insurers are treading gingerly around the issue of health care repeal, putting them at odds with the Republican base on a fundamental question.

Starting in 2014 the law requires most people to have coverage through an employer or a government program or by buying it themselves. Those who refuse face a tax penalty from the IRS, unless they can show financial hardship.

Insurers argue that if they are going to be forced to issue policies to people in poor health — as the law requires in 2014 — then everybody has to get into the insurance pool. It’s exactly the same case the administration is making in court against the state attorneys general.

James Gelfand, health care policy director of the U.S. Chamber of Commerce, said he expects insurers to focus on arcane details of the complex law that make a difference to their bottom lines.

“The are going to have a different opinion on how to address health care than the tea party does, and it does hinge on the individual mandate,” he said. “That’s the biggest difference between the insurance companies and the other parts of the GOP constituency.”