Rich Lowry writes at National Review Online about Republican presidential nominee Donald Trump’s role in exposing fissures within the GOP.

Less than a month before the election, the Republican speaker of the House says he won’t defend or campaign with his party’s presidential nominee. The nominee has responded by slamming the speaker on Twitter, and his campaign manager is accusing some (unnamed) elected Republicans of sexual harassment against her.

The Donald Trump campaign and the Republican party show every sign of entering into an ugly death spiral. The revelation of the Trump Access Hollywood tape last Friday occasioned a historic rupture, with elected Republicans around the country denouncing Trump and calling on him to step aside.

Any hope of Trump turning a corner with his relatively competent second debate was dashed when House Speaker Paul Ryan told his colleagues that he is concentrating on saving his House majority as a check on Hillary Clinton.

It is a fact that one out of two major-party presidential campaigns fail. Some fail badly. But the GOP may be about to experience an unprecedentedly wrenching debacle because its nominee is an ideological interloper with no impulse control or regard for political norms. No matter how bad or weird the campaign seems now, it could get worse and stranger still.

Bob Dole was a horrible presidential candidate and not a particularly conservative Republican. But he was an honorable man who had a loyalty to things bigger than himself, including his political party. When Republicans had to cut him loose in 1996 to try to save their congressional majorities, he was a good and loyal solider.

Does anyone expect that of Donald Trump? His investment in the party is nil, and he takes all slights personally, whether they are from Alicia Machado or the speaker of the House.

The Access Hollywood tape was a tipping point. In isolation, perhaps Republicans could have looked beyond it. But after so many controversies and interventions and alleged pivots, the dam finally broke.