WASHINGTON Sens. John McCain (R-Ariz.) and Lisa Murkowski (R-Alaska) in recent weeks have both lambasted the partisan, closed-door process Republicans have used to try to repeal the Affordable Care Act, a law that affects about one-sixth of the nations economy.

Yet, peculiarly, the lawmakers ended on opposite sides of a critical vote on Tuesday that opened debate on the Senate health care bill.

Battling brain cancer, McCain returned to the Senate from Arizona and cast the deciding vote on the so-called motion to proceed, which advanced legislation to repeal and possibly replace Obamacare. The measure passed by a narrow 51-50 margin, with Vice President Mike Pence casting the tie-breaking vote.

McCain then took to the floor and, in true McCain fashion, blasted his party for crafting legislation in secret, without any hearings and outside of the normal committee process.

Lets trust each other. Lets return to regular order, the Arizona senator said, repeating past criticisms of how the legislation was crafted. Weve been spinning our wheels. Were getting nothing done.

All weve managed to do is make more popular a policy that wasnt very popular when we started trying to get rid of it, he added, referring to Obamacare.

Despite his vote to begin debate on the matter, however, the Arizona senator indicated he would not vote for the Senate health care legislation as it currently stands, something he called a shell of a bill.

Meanwhile, Murkowski, a moderate Republican with long-standing reservations about the GOP bill, was one of only two GOP senators who broke with their party on the motion to proceed. (Sen. Susan Collins of Maine did so as well.)

In a statement released after the vote, Murkowski laid out her rationale for opposing debate on the Senate health care bill. She, too, expressed a desire to return to a more open, bipartisan process on health care.

I have repeatedly said that health care reform, and especially major entitlement reform, should go through the committee process where stakeholders can weigh in and ideas can be vetted in a bipartisan forum, she said. I voted no today to give the Senate another chance to take this to the committee process.

The difference in approach may simply reflect how ultimately comfortable the senators are with legislation that will have a far-reaching impact on millions of Americans who stand to lose insurance under the GOP bill. Murkowski, for example, has said she opposes other provisions in the legislation, such as those stripping funding from Planned Parenthood and from Medicaid.

McCain, on the other hand, is already facing charges of hypocrisy over his vote to advance legislation that was drafted via a process that he decried.

It was a powerful speech that surely would have packed more punch had he voted against a bill and a process that violated many of the principles he outlined, columnist Jennifer Rubin wrote in The Washington Post .

Others, like Sen. Richard Blumenthal (D-Conn.), said the jury was still out on whether Republicans can depend on McCain to pass their bill.

I think his vote was in some ways less important than his speech ... because I think it shows whats inside him and where hes going to go ultimately, he said.