Maybe we have finally established a lasting legislative principle for both parties: Don’t ever again try to pass major health care legislation using parliamentary gimmicks to avoid a filibuster.

The Democrats, under Barack Obama, followed this route in 2010 after they lost their filibuster-proof Senate majority when Republican Scott Brown unexpectedly won the special election to fill Ted Kennedy’s Senate seat. As a result, final tinkering and technical improvements could not be made in the Obamacare legislation using a House-Senate conference.

What the Senate Republicans have been attempting is far worse. Faced with the expiration of the budget resolution at the end of the month, they have been trying to ram through the Senate a ramshackle bill (named after Lindsey Graham and Bill Cassidy) that would upend the health care system without hearings or a full analysis from the Congressional Budget Office.

According to the Republicans, Graham-Cassidy would return health care decisions to the states and spawn experimentation.

According to virtually everyone else (including policy experts, insurance companies and state Medicaid officials), the legislation would slash Medicaid spending, jeopardize the protections for those with pre-existing conditions, trim benefits and force each state to concoct a new health care system on an unworkable two-year timetable.

Graham-Cassidy is so ungainly that Iowa’s Charles E. Grassley was forced to admit in a telephone press conference with home state reporters, “I could maybe give you 10 reasons why this bill shouldn’t be considered. But Republicans campaigned on this so often that you have a responsibility to carry out what you said in the campaign. That’s pretty much as much of a reason as the substance of the bill.”

That was on par with the argument that Nebraska Republican Sen. Roman Hruska once used to defend a dubious Nixon-era Supreme Court nominee named G. Harrold Carswell: “Even if he was mediocre, there are a lot of mediocre judges and people and lawyers. They are entitled to a little representation, aren’t they, and a little chance?”

Graham-Cassidy is Carswell in legislative guise.

And now the bill is likely to fade away as fast as Carswell’s Supreme Court career, thanks to John McCain. In a repeat demonstration that there are still a handful of senators who can utter the phrase “the world’s greatest deliberative body” without giggling, McCain Friday afternoon all but assured the defeat of Graham-Cassidy by announcing his opposition.

McCain killed an earlier “repeal and not replace” GOP health care bill in July with a dramatic late night “no” vote. This time he more routinely issued a statement stating that he could not support any health care bill without knowing “how much it will cost, how it will affect insurance premiums, and how many people will be helped or hurt by it.”

Privately, most members of the dwindling rational wing of the Republican Party are grateful to McCain for saving them from Mitch McConnell’s folly. Not only does it protect the GOP from the consequences of hastily drafted and ill-considered legislation, but it also frees the Republicans to concentrate on their unstinting enthusiasm for bigger and better tax cuts.

In the only politically astute move that Senate Republicans have pulled off since they embarked on their crusade to repeal Obamacare, GOP leaders are moving toward a budget resolution with room for a $1.5 trillion tax cut.

This effort to claim that economic growth will turn a deficit into a surplus will enrage the balanced-budget brigades. But such fiscal sleight of hand is probably the only way that congressional Republicans can deliver a middle-class tax cut.

The billionaires who fill the Trump administration and control major GOP super PACs may be obsessed with corporate tax rates and trickle-down stimulus for the wealthy. But the only thing that a Republican Congress has the potential to deliver before the 2018 elections that a family earning, say, $90,000 yearly might notice is a four-digit reduction in the household tax bill.

Democrats, relieved by what looks like another Perils-of-Pauline rescue of Obamacare, are entering the first autumn of the Trump years with jaunty expressions on their faces. First the president cut a three-month budget-and-debt-ceiling deal with Charles E. Schumer and Nancy Pelosi — and now McConnell has once again played Charlie Brown with the football on Obamacare.

But the Democrats should not feel too smug about their own health care sense of superiority.

Before McCain torpedoed Graham-Cassidy, CNN’s planned Monday night tag-team health care debate seemed likely to garner surprisingly high ratings for a prime-time policy discussion. The 90-minute town hall is slated to pit Graham and Cassidy against independent socialist Bernie Sanders and Minnesota Democrat Amy Klobuchar.

The Republican strategy has been to portray Sanders’ Medicare-for-all proposal as the official position of the Democratic Party. Even though Klobuchar — who is running for re-election in 2018 — has not endorsed the plan, Sanders is apt to grab the TV spotlight as he talks about the benefits of universal health care while skirting all discussions of the high taxes needed to pay for it.

Senate Democrats mulling the 2020 presidential race like Elizabeth Warren, Cory Booker, Kirsten Gillibrand and Kamala Harris have endorsed Sanders’ legislation. But ambitious Democrats on the ballot in 2018 — including Sherrod Brown in Ohio and Christopher S. Murphy in Connecticut — have proven far more cautious about embracing legislation that would effectively end employer-paid health insurance.

Of course, overshadowing the CNN debate is McCain’s political courage as the indomitable “no” man. But McCain aside, the question remains: Why do congressional Republicans always need to be saved from themselves?

Roll Call columnist Walter Shapiro is a veteran of Politics Daily, USA Today, Time, Newsweek and The Washington Post. Follow him on Twitter @MrWalterShapiro.