McCain had a lifetime 81% conservative voting score with the conservative Club for Growth. True GOP moderates like Maine Sen. Susan Collins and Alaska Sen. Lisa Murkowski have CFG scores of 35% and 55% respectively. The Heritage Foundation gives McCain a 60% lifetime rating, as compared to 24% for Collins and 34% for Murkowski.

What McCain was is a senator willing to work with Democrats to get things he cared about done. Whether it was with Wisconsin Sen. Russ Feingold on campaign finance reform or Massachusetts Sen. Ted Kennedy on immigration, McCain demonstrated a willingness throughout his political career to compromise in pursuit of achieving broader goals.

"The most revered members of this institution accepted the necessity of compromise in order to make incremental progress on solving America's problems and defend her from her adversaries," McCain said in a speech on the Senate floor shortly after being diagnosed with the deadly brain cancer that eventually killed him. "That principled mindset, and the service of our predecessors who possessed it, come to mind when I hear the Senate referred to as the world's greatest deliberative body. I'm not sure we can claim that distinction with a straight face today."

That last line is a dagger -- mostly because it is 100% true.

The Senate -- and broader Congress -- that McCain joined in the 1980s is not even close to the one he left late this decade. Over the past 10-ish years, Senate Republicans -- following the lead of their House GOP counterparts -- has become increasingly ideologically consistent and conservative. This chart, built by The Washington Post's Philip Bump using vote data from VoteView , shows the rise of conservatism within the Senate GOP ranks:

The reason is simple: Right around the rise of the tea party movement in 2009-2010, the word "compromise" became a dirty word in Republican politics. Compromise to many Republicans began to be regarded as just a synonym for capitulation. The prevailing sentiment among this new generation of conservatives was that the likes of George W. Bush -- and the Republican leaders in both parties -- had given away too much in the name of compromise with Democrats. Compromise always favored Democrats, they believed. The new view was that conservatives needed to stand on principle -- and, as importantly, punish those faux conservatives who promised to hold the line when running for re-election and then "went Washington" as soon as they got within the boundaries of the nation's capital.

In 2010 alone, three GOP senators -- Murkowski, Indiana's Dick Lugar and Utah's Bob Bennett -- lost bids for re-election. (Murkowski ran a write-in campaign in the general election and won.) McCain was on the ballot that same year, and faced a ideological challenge from former Rep. J.D. Hayworth. The campaign McCain ran reflected the drastic changes afoot in his party. The incumbent dumped more than $20 million into the primary race and famously/infamously ran a tough-on-immigration campaign ad that featured him pledging to "complete the danged fence."

McCain won that race convincingly, but at a cost. Even he was forced to bend amid the swirling winds overtaking the party. (This was not the first time McCain had chosen political advantage over principle; after his support of a comprehensive immigration reform nearly cost him the Republican presidential nomination in 2007, he walked away from it -- a key decision in his eventual march to the 2008 nod.)

By the time McCain stood for re-election again in 2016, the phenomenon of Donald Trump had seized the party. Politicians who fashioned themselves conservative compromisers -- Marco Rubio, Jeb Bush and John Kasich, to name three -- were left in the dust by Trump who, ignoring his Democratic past and all-over-the-map policy pronouncements, channeled the unapologetic conservatism that many Republicans in Congress had run and won on over the past decade.

A single moment symbolizes the state of the party in that moment. In July 2015, just days after formally announcing his candidacy, Trump said this of McCain at a campaign event in Iowa: "He's not a war hero. He was a war hero because he was captured. I like people that weren't captured."

The presumption within the political class was that with that single comment, Trump had ended his campaign before it had even begun. "Donald Trump might finally have crossed the line," read the lede of Politico's news story on the moment. After all, no matter what you thought of McCain's politics, it's impossible to question his service to the country -- most notably the 5-plus years he spent in a North Vietnamese prison camp.

Except that Trump's comment didn't end his campaign, it boosted it. The Republican activist base hated McCain because he had the audacity to work with Kennedy on immigration, because he was unwilling to sign up for every single conservative policy no matter his own personal views. That sort of perceived apostasy was exactly what Trump was running to rid the party of -- and the GOP base cheered rather than jeered his comments about McCain.

The simple fact is this: The current political world in which we live isn't one McCain -- or those he served with for his first two decades in Congress -- would even recognize. If John McCain ran for the Senate in Arizona for the first time in this environment, he almost certainly would lose to a more ideologically consistent Republican who promised unwavering support to Trump. Primaries in the age of the tea party and Trump are something every Republican "establishment" politician now live in fear of because even the slightest hint of criticism of Trump could put you on the wrong side of the ledger when all the votes are counted. Forget working across the aisle with Democrats. That's a political death wish.

In a farewell statement, which was read Monday by spokesman Rick Davis two days after McCain's death, he said this: "We are three-hundred-and-twenty-five million opinionated, vociferous individuals. We argue and compete and sometimes even vilify each other in our raucous public debates. But we have always had so much more in common with each other than in disagreement. If only we remember that and give each other the benefit of the presumption that we all love our country we will get through these challenging times. We will come through them stronger than before. We always do.

"Ten years ago, I had the privilege to concede defeat in the election for president. I want to end my farewell to you with the heartfelt faith in Americans that I felt so powerfully that evening. I feel it powerfully still.

"Do not despair of our present difficulties but believe always in the promise and greatness of America, because nothing is inevitable here. Americans never quit. We never surrender. We never hide from history. We make history."

The simple fact is that our politics is simply not conditioned to produce -- or promote -- another John McCain. Pro-Trump conservatives will take that as a good thing. Out with the RINOs and all that. But, I'd ask you to scroll back to the top of this post and look at McCain's vote ratings by the two most notable conservative outside groups in the country. John McCain was no moderate. He was open to compromise. That distinction has been almost entirely destroyed in the rush for unquestioning political fealty.

"Incremental progress, compromises that each side criticize but also accept, just plain muddling through to chip away at problems and keep our enemies from doing their worst isn't glamorous or exciting," McCain said from the Senate floor in 2017 . "It doesn't feel like a political triumph. But it's usually the most we can expect from our system of government, operating in a country as diverse and quarrelsome and free as ours. Considering the injustice and cruelties inflicted by autocratic governments, and how corruptible human nature can be, the problem-solving our system does make possible, the fitful progress it produces, and the liberty and justice it preserves, is a magnificent achievement."

Amen.