WASHINGTON (Reuters) - The Senate will wait more than two weeks before acting on a bill to permanently fix the flawed formula for reimbursing Medicare physicians, after an April 1 deadline to start a 21 percent cut in payment rates.

Senate Republican and Democratic leaders said early on Friday that they would take the bill up when they return on April 13 from an Easter/Passover break.

The measure, a rare bipartisan achievement in a deeply divided Congress, was overwhelmingly approved on Thursday by the House of Representatives.

Senate Majority Leader Mitch McConnell said he has been reassured that the delay would not cause doctors to see lower Medicare payments due to the lag time in the normal processing of payments from the health care program for seniors.

"They can handle a two week gap here," McConnell said after a marathon session to pass a budget. "We'll turn to it very quickly when we get back. I think there's every reason to believe it's going to pass the Senate by a very large majority."

The measure drafted and driven forward by Republican House Speaker John Boehner and Democratic Leader Nancy Pelosi would fix a long-standing problem with how Medicare pays doctors.

A 1997 budget-cutting bill reduced the payment rates based on a flawed formula linking doctor pay to economic growth, but Congress has routinely passed temporary fixes to forestall cuts that have proven costly.

The measure approved 392-37 by the House would create a new payment formula focused on the quality of care. To help pay for these higher rates, the bill would also impose higher premiums on wealthier Medicare beneficiaries.

However, the proposal would still add $141 billion to U.S. deficits over 10 years, according to congressional forecasters, sparking opposition from some fiscal conservatives.

While the measure has strong support in the Senate, the delay could give opponents time to sway senators against the plan.

One of the government's largest social safety net programs, Medicare is health insurance that serves 54 million elderly and disabled people.

Under the plan, a Medicare recipient with annual income of between $133,000 and $160,000 would see their Medicare premium share increase from 50 to 65 percent, and a recipient with annual income between $160,000 and $214,000 would pay 75 percent rather than 65 percent.

(Reporting by David Lawder and Susan Cornwell; Editing by Tom Heneghan)