John McCain implored colleagues to “return to regular order.” Senators aren’t sure they can do that.

WASHINGTON — Sen. John McCain (R-Ariz.) returned to the Senate floor on Tuesday, looking, in his words, “a little worse for wear,” but strong enough to cast a vote to implore his fellow senators to seek a bipartisan compromise to reform the Affordable Care Act.

The Senate, he said, has suffered from the partisan bickering that drove the health care debate, as he cast a vote to begin debate on an unknown bill to begin health care reform.

“We’re not getting much done apart,” McCain, who last week revealed he had brain cancer after surgery uncovered a glioblastoma, said. “I don’t think any of us feels very proud of our incapacity. Merely preventing your political opponents from doing what they want isn’t the most inspiring work.”

In interviews after Republicans approved the motion to begin debate on health care by one vote, senators cast doubt on their ability to answer the challenge to bipartisanship placed before them by McCain. All senators were hopeful, even chagrined Democrats, but consistently pointed to a lack of cooperation from the other party as an impediment to consensus.

Senators maintained their broad faith in the institution to which they have been elected. But their faith in the body’s efficacy appeared shaken.

“We always do our best work when we work across party lines,” Sen. Lamar Alexander (R-Tenn.) said in an interview. Alexander chairs the Senate’s Health, Education, Labor and Pensions committee, which has not held a single hearing on the health care bill with Sen. Mitch McConnell (R-Ky.) overseeing the process.

“I think what [McCain] was suggesting is [that] we can do better as a United States Senate — and I agree with that,” Alexander said.

Sen. Heidi Heitkamp (D-N.D.) said Democrats have “just begun to fight” after the GOP began debate on health care reform.

“I worry that the Senate forgets it is supposed to be the conscience of the nation, not just a political sounding board.”

“I think the Senate can be functional,” Heitkamp said of the body’s increased partisan tension. “It’s a matter of people deciding it can be functional.”

Democrats have long called for Republicans to hold hearings on their health care proposals. Republican senators said on Tuesday the unlimited amendment process that will begin on Wednesday will serve to give every senator their chance to publicly shape reform.

“I don’t know what’s more American than that,” said Sen. John Kennedy (R-La.). “Shame on the Democrats for voting against the chance to have a debate.”

That partisan theme ran through the minds of senators from both parties as they talked to reporters. “It’s a sad day for the Senate to see this railroaded through this way,” said Sen. Chris Van Hollen. A Democrat from Maryland, Van Hollen said Americans should not be proud of the Senate after Tuesday’s vote.

Sen. Cory Booker (D-N.J.) concurred: “This is not the way the world’s most deliberative body should function.”

Sen. Thom Tillis sees the vote very differently. The North Carolina Republican said the amendment process will force senators to forge a bipartisan compromise out of necessity to pass a bill and reform the health care system.

“The whole point of the deliberative body is any Senate member has the same amount of power to stop things,” Tillis said. “The institution is inherently partisan, and what you try to do is come together on things where you can find those of us who are willing to work together.”

Sen. Patrick Leahy has represented Vermont in the Senate since 1975. The Democrat said he hoped the Senate could return to the era of bipartisan negotiation he bore witness to in the 1980s and 1990s. “I worry that the Senate forgets it is supposed to be the conscience of the nation, not just a political sounding board,” the senator said.

For Sen. Mike Crapo (R-Idaho), it’s about incremental progress. McCain’s bipartisan vision is a good one, Crapo said, but is not necessarily achievable in the short term — particularly on health care.

“[The Senate’s} working,” the Republican said, “but one could argue it could work better.”