The GOP’s embrace of Paul Ryan’s Medicare-killing budget must be one of the greatest political miscalculations of all time. I have assumed (a) the decision to go all-in on Ryan’s budget was the result of the Beltway GOP’s isolation from voters, and (b) that they would quietly let it drop once they realized how badly the idea was bombing.

As for the second second — right after Easter recess it seemed some among the GOP establishment were trying to make Ryan’s budget go away. But the hysterical reaction to Newt Gingrich’s criticism of it revealed the Republicans are, indeed, married to Ryan’s budget. Maybe they didn’t intend to be married to Ryan’s budget. Maybe they woke up in a Las Vegas motel room with the Ryan plan, a marriage license and a hangover. But they are married to it. For better or worse.

As for the first assumption — according to Glenn Thrush and Jake Sherman at Politico, Beltway Republicans were given all kinds of warnings that their plans for Medicare would blow up in their faces. According to Thrush and Sherman, the Republicans’ nearly unanimous House vote for the budget was the result of “colliding principles and power politics” and came about only after days of fierce, behind-closed-door infighting.

GOP pollsters, political consultants and House and NRCC staffers vividly reminded leadership that their members were being forced to walk the plank for a piece of quixotic legislation. They described for leadership the horrors that might be visited on the party during the next campaign, comparing it time and again with former Speaker Nancy Pelosi’s decision to ram through a cap-and-trade bill despite the risks it posed to Democratic incumbents.

Are they kidding? The cap-and-trade bill might have hurt some Dems in conservative House districts, but the Ryan vote is going to hurt Republicans across the board. No way is cap-and-trade a vital issue to most voters on the same level as Medicare.

Anyway, the short story is that even Republicans with misgivings voted for the plan for fear of being accused of not being pure enough on the deficit issue.

“The feeling among leadership was, we have to be true to the people who put us here. We don’t know what to do, but it has to be bold.”

Another GOP insider involved to the process was more morbid: “Jumping off a bridge is bold, too.”

It’s like they’ve been playing some version of Truth or Dare — either embarrass yourselves to the Tea Party or to the general public.

Update: Rupert Murdoch The Wall Street Journal tells its readers that they must choose between “ObamaCare” and Paul Ryan’s version of “entitlement reform.” The Right is married to the Ryan plan, I tell you.

Related — “The Elephant in the Green Room.”