WASHINGTON - President Barack Obama is making a mistake on health care by insisting on a government insurance option for the middle class, several Republicans said in a letter to the White House released Monday.

It could cost him chances for broad support across the political divide, the nine lawmakers, all members of the Senate Finance Committee, warned.

Leaders of the Finance panel, which has the best odds of producing a bipartisan bill, are working against a self-imposed deadline for moving the legislation through committee this month. But tensions have been rising since Obama recently affirmed his strong support for including the option of a public insurance plan.

"At a time when major government programs like Medicare and Medicaid are already on a path to fiscal insolvency, creating a brand new government program will not only worsen our long term financial outlook but also negatively impact American families who enjoy the private coverage of their choice," said the letter, signed by all but one of the Finance Republicans.

Sen. Orrin Hatch, R-Utah, said Democrats would live to regret it if they insist on a public plan.

"Democrats know that if they go to a totally partisan approach like the president has suggested they're going to eat that the rest of their lives," said Hatch, who circulated the letter to Obama.

"I'll be glad to help them, but not with a public plan," Hatch, referring to the Democrats, told Fox News.

Obama says his plan would allow Americans to keep private coverage. But Republicans say once a government insurance program is created, it will eventually dominate the market, driving private insurers out of business.

Most Democrats support creating a public plan to compete with private insurers, but even they are divided over critical details.

The one Finance Republican who did not sign the letter was Sen. Olympia Snowe of Maine. Snowe has been trying to find a compromise through which a government plan would be available as a last resort, if health care costs don't come down and many people remain uninsured.