Correction Appended

Though he didn’t ride in on a white horse, Sen. Edward Kennedy (Mass.) was received as the Democrats’ knight in shining armor Wednesday when he returned to the chamber for the first time since being diagnosed with a brain tumor in order to cast a decisive vote on a stalled Medicare bill.

Not having voted since mid-May, Kennedy shouted “aye” over the raucous, bipartisan applause that brought the Senate to a standstill for several minutes. His surprise appearance and vote on the floor moved some Democratic Senators to tears and shocked Republicans who had earlier appeared confident that they would be able to deny Democrats the one vote they needed to overcome a GOP filibuster of the Medicare measure.

Through it all, a red-faced Kennedy beamed.

After Kennedy voted and it was apparent that Democrats would get the 60 votes they needed, the number of Republicans voting with Democrats swelled to 18, allowing the measure to get past a procedural hurdle by a vote of 69-30. Only nine Republicans had voted for the measure on June 26, but Democrats fell one vote short of ending the filibuster.

Kennedy was absent after surgery in June to reduce the size of his tumor and subsequent chemotherapy and radiation treatments. His cancer was diagnosed shortly after he suffered a seizure at his home in Massachusetts on May 17.

Kennedy was not expected to return the Senate until September at the earliest.

In a statement Kennedy said, “I return to the Senate today to keep a promise to our senior citizens — and that’s to protect Medicare. Win, lose or draw, I wanted to be here. I wasn’t going to take the chance that my vote could make the difference.”

With the filibuster broken, the Medicare bill passed easily.

A cloak of mystery surrounded Kennedy’s return. Democratic sources said Kennedy alerted Senate Majority Leader Harry Reid (D-Nev.) on Tuesday night that he would be present Wednesday, but Reid and other Democrats kept it under wraps until shortly before the vote was called.

Capitol Police shut down the North Door of the Senate in order to keep press at bay as Kennedy entered. In fact, only one reporter and one photographer witnessed his return. Asked how he was feeling, Kennedy replied, “Good.”

As the vote began, Democratic Senators poured into the chamber to take their seats and wait for Kennedy’s arrival. He was ushered in with great fanfare by his son, Rep. Patrick Kennedy (D-R.I.), presumptive Democratic presidential nominee Sen. Barack Obama (Ill.), fellow Massachusetts Democratic Sen. John Kerry and close friend Sen. Chris Dodd (D-Conn.).

Indeed, Kennedy’s visit completely overshadowed the rare appearance in the chamber by Obama, who had earlier in the day been the one to watch on the Senate floor.

“I have been in Congress now 26 years, and I’ve seen a lot of things in my tenure in Congress,” Reid said after the vote. “I’ve never seen a more moving minute than the time Sen. Kennedy walked onto the Senate floor today.”

Reid noted that the applause that welcomed Kennedy’s triumphant return came from all corners of the chamber because “everyone recognizes this was an act of courage.”

“Kennedy was in the United States Senate when Medicare was passed, and Ted Kennedy wasn’t going to let Medicare be destroyed,” Reid said. “His vote made the difference.”

Asked what tipped the scales so heavily in favor of the Democrats on the issue this time, Reid gave all the glory to Kennedy, saying he alone was the “reason we got the extra votes.” Republicans, he said, “knew the die had been cast” after Kennedy had voted.

Senate Finance Chairman Max Baucus (D-Mont.),who sponsored the Medicare bill on the floor, called it “quite an historic moment” — not only because of Kennedy’s return, but also because of the importance of the measure itself, which would prevent doctors who serve Medicare patients from taking a 10.6 percent pay cut.

Yet like Reid, Baucus gave all the credit for the bill’s passage and its veto-proof majority to Kennedy, saying: “We got this big victory because of Ted. He made this victory happen.”

Kennedy wasted no time in heading back to Massachusetts to resume his treatments, but his closest ally, Dodd, stood with Democratic leaders on his behalf. He said Kennedy’s doctors “were not happy” about his decision to travel to Washington, but Dodd quipped, “Ted is not in the habit of listening to doctors and decided to be here.”

“The Senate owes him a great deal, seniors owe him a great deal,” Dodd said. “It was good to see the lion back on the Senate floor.”

The Medicare bill for which Kennedy returned was significant because doctors had warned that they would have to stop treating Medicare patients if the pay cut went into effect. In fact, the reduced reimbursement rate officially went into effect July 1, but the Centers for Medicare and Medicaid Services indicated it would not process claims until mid-month, giving Congress time to pass a bill.

Still, Senate Republicans had vigorously opposed the measure, which passed the House 355-59, because they said the bill made unnecessary cuts and changes to the Medicare Advantage program, which is run by private insurers. The president has threatened to veto the measure, but the American Medical Association and the AARP mounted a massive grass-roots lobbying campaign over the July Fourth recess designed to pressure Senate Republicans into changing their votes.

Even before Kennedy showed up, several GOP Senators were wavering both publicly and privately Wednesday.

Two hours before the vote, Sen. Bob Corker (R-Tenn.) said he was not going to make up his mind until the vote was called, and he criticized both parties for using the bill as a political tool.

“I’ve got concerns about the way both sides have handled this,” Corker said. He added that the fact that President Bush might veto the measure “to me, candidly, is a nonissue.”

Other Senators acknowledged they had been thinking about changing their votes but expressed an unwillingness to be the one Republican to turn the tide for Democrats.

“I don’t think the underlying bill is so dramatically bad. I just don’t think it’s the right way for us to get there,” said Sen. Mel Martinez (R-Fla.) prior to the vote. But he allowed that if the measure secured the 60 votes it needed, then he would likely support it.

“If it doesn’t fail and it appears there’s going to be 60 votes, then I will vote to support that.”

Sens. Kay Bailey Hutchison (R-Texas) and Arlen Specter (R-Pa.) refused to say how they would vote Wednesday, and both waited until the measure garnered 60 votes before supporting it themselves. Several other GOP Senators, such as Martinez and Corker, also waited until it was clear the bill would pass.

After the vote, Hutchison explained her position.

“We had a very dramatic moment here on the floor of the Senate, and I think there wasn’t a person in the room or the gallery that wasn’t thrilled to see Sen. Kennedy back and looking so good,” Hutchison said on the floor.

But she added, “I want to say, though, that I don’t think this was the Senate’s finest hour. I want us all to remember that in the United States Senate we have had a long tradition of bringing up legislation, having amendments and then voting on the legislation. That was not the case in the bill that was before us today.”

Despite what appears to be thin support among Republicans for the measure, Reid appeared confident that he would hold onto the votes necessary to stave off the promised presidential veto, a margin that has some comfort given 69 Senators favored the measure on its second run through the Senate. Just 67 votes are needed to override a veto.

Tim Taylor contributed to this report.

Correction: May 11, 2008

The article incorrectly reported the number of Republicans who originally supported a bill to stave off a cut in doctor reimbursements under Medicare. There were nine Republicans who voted for the bill.