The lede to this column is a deep, guttural groan that originates in the throat and expands into the lungs before collapsing in the pit of the stomach. How do you spell hmmmgrrrungh?What else is there to say about House Republicans' inability to get something right? And I say this with compassion, I really do. Because seriously? It's over. Done. Kaput.With Kevin McCarthy's recent response to the simplest question about GOP accomplishments in Congress, from the friendliest interviewer, Sean Hannity, a GOPer could hope for, the future may as well be called Democrat.Here's what McCarthy offered if you happened to be away exploring conspiracies about liquid water on Mars: "Everybody thought Hillary Clinton was unbeatable, right?" he said. "But we put together a Benghazi special committee, a select committee. What are her numbers today? Her numbers are dropping. Why? Because she's untrustable."The consequences of McCarthy's sleight of tongue can't be overstated. It wasn't just a Washington gaffe, when someone accidentally tells the truth. It was a self-inflicted, potentially fatal wound, not just to McCarthy but to Republicans more broadly, including those running for president.One minute McCarthy was the near-certain next speaker of the House; the next he was persona non grata as GOP colleagues, their own minds hurtling through various apocalyptic scenarios, hammered him.McCarthy has since tried to cram the bad genie back into the bottle, but the damage has been done and can't be undone.Essentially, he had handed Clinton the keys to her prison cell. Held hostage these past three years by a series of Republican interrogators about the September 2012 attack in Libya that killed our ambassador and three others, she has been liberated.The Benghazi hearings that led to the private server, that led to the missing 30,000 emails, that led to the FBI investigation that thus far has led only to the conclusion that she was "hackable" have been reduced in the public mind to a political hit job organized to damage her chances of becoming the Democratic presidential nominee.This isn't necessarily the whole of it — House Select Committee on Benghazi Chairman Trey Gowdy and others certainly believe there's more to know — but the cement has set on what McCarthy implied. At the very least, any previous suspicions that Republicans were just out to get Clinton have cleared the bar of reasonable doubt.One can imagine, meanwhile, that Clinton is performing mental pirouettes and grand jetes, dancing circles around the vast right-wing conspiracy, even as she conveys almost sorrowfully how "deeply distressed" she is by McCarthy's admission.Miraculously, she managed not to betray the happy tune coursing through the sunlit savannah of her brain's limbic system: "Born free, as free as . . ." I know, I hate it, too. Maybe she and John Boehner can get together and perform a duet of "Zip-a-Dee-Doo-Dah."Yes, this New McCarthyism is that serious. The Republican Party, which deserves better than its parts, has suffered a damaging blow when it can ill afford another. Already in disarray with constant inner conflict, the House also faces Boehner's imminent retirement and yet another debt-ceiling crisis looming.McCarthy should tar and feather himself and ride out of town on a donkey. Then again, couldn't one as easily say, as Howard Dean recently suggested on MSNBC's "Morning Joe," that, good grief, McCarthy merely bumbled? That this, too, shall pass?Not on your life. Does anyone really think Hillary Clinton will let this pass?At best, McCarthy can try to be convincing when he insists that the Benghazi investigation wasn't politically motivated (cough, cough, this darned weather). Here, let me help you, sir: "What I meant was that the Republican Congress' greatest accomplishment, by way of its investigations into Benghazi, is to have revealed that Hillary Clinton should never be president."You see the problem. McCarthy should never have mentioned the word Benghazi in the context of political advantage for the now very obvious reasons.How could someone aspiring to be speaker of the House, No. 2 in line behind the vice president to become president if so required, fail to know this? House Republicans will have to answer this question for themselves when they vote for leadership next week.Meanwhile, unless Gowdy discovers Clinton's fingerprints on a grenade retrieved from the diplomatic compound in Benghazi, she has every right to denounce any future claim or question as the grandstanding of admitted political scammers.That growling sound you hear rolling down Capitol Hill and across the Potomac isn't just thunder.