BOSTON —

Republican Sen. Scott Brown, reversing a position he took earlier this month, said Monday he will vote against the House Republican budget because he cannot support U.S. Rep. Paul Ryan’s proposal to transform Medicare into a voucher system.

“While I applaud Ryan for getting the conversation started, I cannot support his specific plan — and therefore will vote “no” on his budget,” Brown wrote in an op-ed in Politico.

The Massachusetts senator, who is seeking re-election in 2012, had been under fire from Democrats in his state after telling a gathering of business leaders in Georgetown, Mass., that he planned to vote for the GOP budget even though he did not expect it to pass.

“The leaders will bring forward (Ryan’s) budget, and I will vote for it, and it will fail,” Brown said at a May 13 luncheon, according to a report by the Newburyport Daily News.

Several days later, Brown’s office issued a statement saying that Brown supported the overall direction Ryan’s budget took toward reducing spending, but declined to say whether he would support the Medicare overhaul or vote for the budget.

The GOP plan passed by the House would cut government deficits by $6.2 trillion over the next decade. One of its most contentious provisions calls for eventually transforming Medicare into a voucher-like system in which private insurance plans, not the government, pay medical bills.

Ryan, a Wisconsin Republican, chairs the House Budget Committee.

In Monday’s op-ed, Brown listed several objections to the Medicare proposal.

He said he was concerned that as health care expenses continue to grow, the cost of private insurance plans will rise faster than government premium support, forcing the elderly to pay even higher deductibles and co-pays.

“Protecting those who have been counting on the current system their entire adult lives should be the key principle of reform,” Brown wrote.

Medicare has already been cut to help pay for President Barack Obama’s health care plan, he said.

Congress should instead cut waste and fraud and make other improvements to the traditional Medicare system, Brown said. He also said savings could be found by increasing congressional oversight of Medicare reimbursements and through medical liability reform that would cut down on frivolous malpractice lawsuits.

“We can work inside of Medicare to make it more solvent,” Brown wrote.

Brown’s earlier position on the GOP budget had been sharply criticized by Democrats in Massachusetts, where Brown won an upset victory in the Jan. 2010 special election to succeed the late Sen. Edward Kennedy.

Those critics included Newton Mayor Setti Warren, one of the announced Democratic challengers in the 2012 Senate race.

The Democratic Senatorial Campaign Committee, in a statement Monday, said Brown was trying to have it both ways on Medicare and that he still had not made clear whether he was open to privatizing it.

“Brown’s op-ed today was certainly a tantalizing read, but there is still so much that Brown is refusing to tell his constituents about where he stands when it comes to Medicare and protecting seniors,” said Matt Canter, spokesman for the DSCC. — AP