Breaking with the traditional stance of his own party, President Barack Obama used his State of the Union address to endorse medical malpractice reform that doctors say is sorely needed to bring down health costs.

But in an unusual twist, some conservatives are balking at legislation introduced by House Republicans to curb malpractice awards, citing concern that it could undermine states’ rights.

Such resistance has made the job harder for those lobbying for the changes, including the powerful American Medical Association, whose members hit Capitol Hill last week to press lawmakers to rein in court awards.

Meanwhile, trial lawyers, who have long been the fundraising stalwarts of the Democratic Party, are suddenly taking an interest in the new tea-party-backed GOP lawmakers who may be critical to stopping the medical malpractice measure in the House.

The American Association for Justice, which lobbies for trial lawyers, is accustomed to fighting the legislation, which comes up almost every session.

“This isn’t our first rodeo,” said spokesman Ray De Lorenzi.

But last week even De Lorenzi took note of what he described as “GOP infighting  on the bill” as the House Judiciary Committee considered a malpractice measure that would impose $250,000 limits on noneconomic damages.

Two Texas Republicans on the committee, Reps. Ted Poe and Louie Gohmert, objected to the measure, which would apply to federal and state courts where state legislatures or voters had not already approved malpractice restrictions.

Poe and Gohmert said they did not want Congress to override state constitutions that bar limits on malpractice awards in state courts.

“It’s up to the states whether they want to run off their good doctors,” Gohmert said.

Twenty-eight states have imposed some limits on noneconomic or economic damages.

In justifying federal authority to impose the malpractice curbs, the legislation states that litigation affects interstate commerce by contributing to the high cost of health care. Some Democrats said it was ironic that even as they cite interstate commerce as a reason to regulate health lawsuits, Republicans have challenged key provisions of the newly enacted health care law in court, arguing it does not meet the Commerce Clause threshold.

Matt Webb, a senior vice president at the U.S. Chamber of Commerce’s Institute for Legal Reform, which is lobbying for the malpractice curbs, agreed that the debate has taken a new twist.

“There are a lot of chaffs up in the air regarding the Commerce Clause and the 10th Amendment, as well,” he said. The 10th Amendment, which has become a rallying cry for the Tea Party, relegates powers to the states that are not granted to the federal government by the Constitution.

But Webb, who was optimistic the House will approve the malpractice curbs, argued that malpractice verdicts were having an adverse impact on interstate commerce.

Doctors in states with no limits say the threat of large malpractice awards has sent some of their colleagues packing in search of friendlier legal turf. Marilyn Heine, a suburban Philadelphia physician, said she underscored that point last week when she visited the offices of her representatives, Rep. Mike Fitzpatrick (R) and Sens. Pat Toomey (R) and Bob Casey (D), as part of the AMA’s national advocacy conference. Heine related how a local neurosurgeon had left Pennsylvania and moved to Texas, which has imposed malpractice limits. Pennsylvania state courts are barred by the state constitution from imposing malpractice award limits.

Even though the legislation’s fate is unclear, Heine said the lobbying trip was worth it.

“It’s about relationship-building and staying on their radar screen” she said.

E. Coy Irvin, a family physician from South Carolina, said that while doctors often shy away from advocacy, he has urged his colleagues to come to Capitol Hill, if only to size up the lobbying presence of the opposition, whom he referred to as “the suits in the room.”

While malpractice legislation has stalled in the Senate in the past, Irvin expressed hope that centrist Democrats would support it because of political pressure as the 2012 election approaches.

Other proponents of the malpractice curbs say the legislation faces an uphill battle of even getting considered in a Senate controlled by Democrats, who have long been beneficiaries of campaign contributions from trial lawyers.

Last year, the AAJ’s political action committee made almost $3.7 million in political contributions, almost all of it to Democrats. The association also spent $3.9 million on lobbying, with $470,000 of that paid to the Patton Boggs law firm.

“It is not a pretty scenario,” said Lawrence Smarr, president of the Physicians Insurers Association of America, which supports the malpractice legislation.

But proponents of malpractice legislation such as the AMA and the chamber are also among the top spenders on lobbying and are active in political campaigns. The AMA’s PAC contributed $1.4 million to federal candidates and parties last year, with more than half going to Democrats.

Ronald V. Miller, a personal injury lawyer from Baltimore who has written about the malpractice issue on his blog, said that while doctors have done a better job of winning the public relations battle, their motive in limiting awards is not entirely altruistic.

“Ultimately what this all about is doctors wanting to increase their income,” he said.