House and Senate Republicans continued their mass defections from the Bush administration’s position on Medicare reforms, voting Tuesday to override President Bush’s veto of legislation that would prevent cuts in Medicare payments to doctors.

The override, which easily passed the House 383-41 and the Senate 70-26, marks the third time Congress has bucked Bush, joining veto overrides last year on a massive water resources bill and last month on the farm bill.

The House Democrats’ rout of the White House was even more dramatic than the 355-59 vote they racked up on final passage of the measure before the July Fourth break. On Tuesday, they added 18 Republicans to their ranks to swamp the veto.

Bush’s Tuesday afternoon veto came after days of quiet lobbying from some Republicans to either sign the bill or use a pocket veto to take it off the political radar.

House and Senate Republicans spent much of their July Fourth recess being attacked by doctors organizations, senior citizens groups and others who supported the bill.

The Senate returned to work last week and passed the Medicare legislation by a veto-proof margin after the ailing Sen. Edward Kennedy (D-Mass.) cast a crucial vote that broke a tenuous GOP filibuster.

Many Republicans argued that issuing a clearly doomed veto would only give Democrats another chance to take shots at Republicans. But Bush remained defiant, and administration officials Monday laid blame for the collapse of GOP opposition at the feet of Senate Republicans.

“It’s not the Democrats who put us in that position. It’s the nine Republicans,” Tevi Troy, deputy secretary of the Department of Health and Human Services, said during a conference call.

Publicly, few Republicans appeared eager to talk about the vote, which for the Senate was the third time in four weeks that lawmakers had been forced to cast a vote on the bill. Senate Minority Leader Mitch McConnell (R-Ky.), for instance, refused to comment on the administration’s rebuke of his Conference.

When pressed by reporters for his thoughts on the broader bill, McConnell would only say, “That issue will be behind us one way or the other later today.”

But privately, Republicans bristled at administration claims that they were to blame for a collapse, arguing that the only reason they had been able to filibuster the previous votes was because of Kennedy’s absence. “We were never there. We held at 39, but only because Kennedy wasn’t here,” one GOP lawmaker explained.

“There’s a lot of finger-pointing going on right now … [but] I don’t know that they could ever have argued we’d be at 40 or 41,” the lawmaker added, arguing that the White House’s insistence on vetoing the legislation has puzzled some in the GOP Conference. “I’m not sure why they’re pushing it. I think everyone on our side agreed that once the dike was broke … we wouldn’t be made to have another vote again.”

Sen. Johnny Isakson (R-Ga.) said that while he originally supported the filibuster because the bill is only a short-term fix to the payment system, at some point Congress should not make doctors and patients pay for its inability to come up with a plan for long-term reform.

“I supported withholding cloture on the first vote because there were some legitimate concerns. … It’s time we open up the patient and do major surgery,” Isakson said. But with a permanent fix far from ready, “the doctors and patients should not be made to suffer because of Congress’ inaction,” he argued.

House Republicans who opposed the measure on final passage before flipping to support the veto override explained that while they were unhappy with their options, they couldn’t support the cuts in doctors’ Medicare payments that a defeat of the measure would have imposed.

“I voted against that bill because a better bill was available and should have at least been brought to a vote,” Rep. Mac Thornberry (R-Texas) said in a statement of his original vote against final passage. “Unfortunately, due to partisan considerations, the better bill was never allowed a vote in either the House or the Senate.

“After the President vetoed the measure, I voted to override the veto — and thus approve — the legislation because July 15 is literally the last day to pass a bill before the 10% cut in Medicare reimbursements would become effective,” the statement continued.

Likewise, Rep. Charles Boustany (R-La.), a surgeon, wanted to pursue a long-term fix to the payment cuts, leading him to vote against the original bill. “That being said, he understands that physicians are hurting and need to be able to see Medicare patients,” spokesman Rick Curtsinger said. “Physicians needed this help, and he’s committed in the long run to change the formula.”