Paul Ryan presides over a committee hearing on Capitol Hill in June. (Manuel Balce Ceneta/AP)

House Republicans face a fateful choice — and not just over who will be their next speaker. It is a choice about whether they want to be a realistic, governing entity or a bomb-throwing band of purists that will, inevitably, hurt the party’s prospects not only for retaining the current GOP majorities in the House and Senate but for retaking the White House as well.

Based on the current evidence, the answer may well be the latter: bomb-throwing purists, at least among enough of the majority to prevent Republicans from functioning.

The ultimate manifestation of this craziness isn’t the departure of Speaker John Boehner (R-Ohio) or the pre-emptive dethroning of Majority Leader Kevin McCarthy (R-Calif.). It’s the jaw-dropping notion that Rep. Paul Ryan is insufficiently conservative to be entrusted with the speakership.

The Wisconsin Republican, chair of the House Ways and Means Committee, is a serious and creative — albeit, from my point of view, wrongheaded — thinker about the country’s budgetary challenges. He is the intellectual leader of the House, if not the party.

One indication of that intellect: He doesn’t want the job.

Rep. Paul Ryan (R-Wis.) is being tapped to become the next speaker of the House, even though he doesn't seem to want the job. Who is this guy? (Gillian Brockell/The Washington Post)

One indication of why he doesn’t: The ultra-conservative faction — actually, conservative is not an accurate adjective for this crowd — is mounting a campaign against him.

Paul Ryan is a Dangerous Pick for Conservatives,” warned RedState.com’s Erick Erickson. He ticked off the evidence of Ryan’s perfidy: “While in Congress, he voted for No Child Left Behind, the Prescription Drug Benefit, TARP, caps on CEO pay, the AIG bill, the GM bailout, the debt ceiling, and now the fiscal cliff.”

Consider, No Child Left Behind was the signature education measure pushed by . . . Republican President George W. Bush. Adding prescription drug coverage to Medicare was the signature health measure pushed by . . . Bush. TARP, the Troubled Asset Relief Program, was the bailout package pushed by ... well, you know.

More troubling to the Ericksons of the world have been Ryan’s dogged efforts to prevent economic calamity — and, by the way, damage to the party — by avoiding government shutdowns and a breach of the debt ceiling. Ryan, Erickson observed, “collaborated with Senate Democrat Sen. Patty Murray (D-Wash.) to raise taxes.”

Note the verb: collaborated — Ryan as Marshal Petain. The offending “tax” was an increase in Transportation Security Administration user fees, raising them a whopping $3.10 per flight. This as part of a deal that brought two years of budgetary peace.

But wait, that’s not all, and Erickson is far from alone. The conservative Web site Breitbart.com featured an interview with NumbersUSA president Roy Beck, who described the prospect of Speaker Ryan as “terrifying,” adding, “There’s nobody in the Republican Party who could be worse than Paul Ryan. He has spent his entire adulthood ideologically connected to the open borders crowd.”

Not only has Ryan endorsed the concept of “earned legalization,” he backed fast-track trade negotiating authority for President Obama and now supports the Trans-Pacific Partnership — derided by conservative bloggers as Obamatrade, as if any deal engineered by this president is inherently unacceptable.

This would all be simply depressing noise were it not for the unfortunate reality that the conservative blogosphere tail wags the congressional dog — or at least enough of it to make the animal incapable of walking.

It’s not simply the House Freedom Caucus of 40 or so radical conservatives. It’s other members — what one lawmaker described to me as the “vote no, hope yes” caucus — cowed into taking crazy positions for fear of primary election challenges.

The Freedom Caucus’s demands from the next speaker, outlined in a questionnaire, include commitments to provide for the filibuster-proof repeal of Obamacare, require that any increase in the debt ceiling be coupled with entitlement reform and refuse to fund the government through temporary spending bills.

Most alarming, they call on any prospective speaker to abide by the so-called Hastert rule against bringing legislation to the floor without support from a majority of the GOP caucus. This is a recipe for disaster in the form of government shutdowns and debt defaults.

If I were Ryan, I would tell the Freedom Caucus to take its demands — and the speakership, for that matter — and shove them.

Because the position is only worth having if those for whom you would speak are willing to be led. And this requires an even more fundamental recognition: that politics remains the art of the possible, not the crayoned scrawl of tantruming preschoolers unable to have it entirely their way.

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