(Amber Ferguson/The Washington Post)

Sens. Mitch McConnell and John McCain have a fundamental difference in their approaches to politics.

The Kentucky Republican counts success almost entirely through political victories, wins and losses best measured by the elections every two years. The Arizona Republican measures success in the worthiness of the fight — a determination that is sometimes influenced by his predilection for playing the “maverick” and the attention that brings.

In their more than three decades together in the Senate, that disparity has never been on display quite like in the past few days. On Tuesday, McCain was a conservative hero, scorned by liberals as a hypocrite. By early Friday morning he was back in liberals’ good graces, the subject of some grumbling from Republicans and on the receiving end of a pointed tweet from President Trump, who earlier in the week called him a “Brave — American hero!”

McCain’s decisive vote, after 1 a.m. Friday, to oppose McConnell, Trump and the overwhelming majority of Senate Republicans on the effort to revamp the Affordable Care Act will help define his career. It was an encapsulation, in less than 60 hours, of how often he goes from friend to foe.

First, after being diagnosed last week with an aggressive form of brain cancer, McCain flew back to Washington on Tuesday to cast a crucial vote allowing Senate Republicans to begin considering their bill. McConnell grew emotional as McCain delivered a 15-minute oratory about returning the chamber to its glory — a world where, in his view, committees, not party leaders, crafted bills and bipartisanship was the norm.

(U.S. Senate)

By 1 a.m. Friday, that warmth toward McCain had turned into fury as he joined two other Republicans, Sens. Susan Collins of Maine and Lisa Murkowski of Alaska, to deny McConnell his last-ditch attempt to keep alive the effort to repeal Obamacare.

“It’s time to move on,” the majority leader said after the bill’s stinging defeat.

It was the most humiliating legislative loss of McConnell’s more than 32 years in the Senate, all the more so because he had shrunk his ambition to a narrow bill that was meant only to serve as a vehicle to open a new round of negotiations with House Republicans.

McCain had issued a pretty clear warning, during his Tuesday speech, that he wasn’t much interested in just chalking up a victory for Republicans.

“Sometimes, I wanted to win more for the sake of winning than to achieve a contested policy,” McCain told his colleagues, not even two weeks removed from the surgery above his left eye that revealed the brain tumor.

A few minutes later, he urged them to join him in rejecting that approach, calling for more across-the-aisle give and take. “It is our responsibility to preserve that, even when it requires us to do something less satisfying than ‘winning,’ ” he said. “Even when we must give a little to get a little.”

Sen. John McCain (R-Ariz.) speaks to reporters at the Capitol hours before casting the decisive no vote against the Republican health-care plan. (Cliff Owen/AP)

This is the single biggest divide between McConnell, 75, and McCain, 80.

McConnell is a proud political pugilist whose very essence is defined by how many wins Republicans chalk up. Every decision in the 10½ years since he became his caucus’s leader has been crafted toward trying to capture and then maintain the Senate majority.

His mantra in the past few weeks was that Republicans had to pass a rewrite of the 2010 health law because they had told their conservative base of voters that they would, ever since Democrats passed it on a party-line vote. Failure would be a political disaster and lead to deep Republican losses in elections ahead.

But McCain’s persona is linked to his expressions of dignity in defeat, willingness to break with his party and eagerness to be seen as above the raw politics of the moment.

As a Navy pilot, he was shot down over Vietnam, tortured and held captive for more than five years. The son of an admiral overseeing the Pacific fleet, he was offered — and turned down — early release ahead of his fellow POWs.

En route to a large defeat in the 2008 presidential campaign, McCain rejected the venom some supporters felt toward his opponent, Barack Obama, calling the future president a “good man.”

But as much as he receives praise for taking principled stands, McCain also draws the ire of critics who see inconsistency in when he invokes these principles and who question whether he at times allows personal animus or a craving for the spotlight to govern those decisions.

Before casting his vote early Friday, McCain seemed to be enjoying, at least a bit, that his vote would upend his party’s plans.

Wait for the show,” he told reporters asking how he would vote as he headed toward the floor, building up some drama for what was about to unfold.

The complicated relationship between McCain and McConnell stretches back long before the current health-care debate.

McCain’s biggest legislative success, aside from national security matters, came in 2002 on a campaign finance law that restricted big donations that national political parties could collect. His opponent throughout that fight was McConnell, who argued that Republicans needed those six- and seven-figure checks to defeat Democrats and their union allies.

McConnell then helped lead the legal battles that would gut that campaign law.

In recent years, McConnell has relied often on McCain’s counsel, not just on national security but also on key institutional rules disputes. They both pride themselves on being protectors of the Senate’s unique procedures that compel bipartisan work, and a few years back McCain served as one of McConnell’s emissaries in disputes with Democrats.

But their bond frayed again over the past several weeks, as the two elder statesmen clashed over the process that culminated Friday morning. After the House passed its unpopular health-care legislation, McConnell tried to find a better, broader version that could get 51 votes just from Republicans, because he knew that Democrats had no interest in working on a bill to repeal Obama’s landmark domestic policy achievement as president.

None of his ideas came close to succeeding, so he came up with a final idea: Just pass a bill with a few of the more popular concepts, so a new round of negotiation with House Speaker Paul D. Ryan (R-Wis.) could commence.

The idea was simple: winning.

To have a chance at winning, Republicans had to pass a bill that left intact much of Obamacare and did little to address the key concerns of McCain and many Republicans.

Sen. Lindsey O. Graham (R-S.C.), McCain’s closest friend, called the proposal “a disaster” and “a fraud” and “horrible politics.”

“I have nothing to add,” McCain chimed in at a Thursday evening news conference.

Once Ryan gave assurances that a new negotiation would take place and that he would not have the House quickly pass the Senate bill, McConnell counted 49 Republican votes.

Murkowski and Collins were already publicly opposed. Only McCain remained undecided.

He will soon go back to Phoenix to begin treatment for his cancer — possibly chemotherapy that will be so debilitating, no one is sure when he might return to the Senate.

As the final votes started, shortly after midnight, McCain stood in the Senate talking to colleagues trying to win his vote. He talked to Vice President Pence, who was there to cast the tiebreaking vote if McCain came on board. He took phone calls, including one from Trump.

But McCain was done with winning for the sake of winning.

He said as much during his speech Tuesday, telling his 99 colleagues that it was time for compromise.

“It doesn’t feel like a political triumph,” McCain said. “But it’s usually the most we can expect from our system of government.”

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