Joe Biden’s decision on Sunday to withdraw from the presidential race—as dramatic an event American politics has seen since Richard Nixon’s 1974 resignation from the presidency—illuminates a crucial divide between the two major political parties. Nixon himself provides a useful marker for how radically the Republicans have been transformed under Trump. Nixon was, famously, a crook who hijacked the powers of the presidency in order to undermine the Constitution. But when push came to shove, Nixon was rational enough to realize he couldn’t govern without the support of his own party. When Republican Party elders—led by the staunch conservative Barry Goldwater—told Nixon the jig was up, he made the unprecedented decision to resign (a move perhaps facilitated by an under-the-table quid pro quo deal to secure a presidential pardon from his successor Gerald Ford).

Donald Trump has never displayed the decency, respect for party cohesion, and civic-mindedness of even that scoundrel Richard Nixon. Trump was twice impeached, in 2020 and 2021. In the second impeachment, seven Republican senators voted to convict a president of their own party. But those seven, although indisputably brave, were not in any way representative of their party. The vast majority of Republicans in Congress stood by Trump during both impeachments.

Under Trump, the GOP has become nothing more or less than a personality cult. In a campaign stop in Iowa in 2016, Trump notoriously boasted, “I could stand in the middle of Fifth Avenue and shoot somebody, and I wouldn’t lose any voters, OK?” The evidence of the last eight years suggests that Trump was, for once, being uncharacteristically modest. In 2021, he incited a mob to attack the Capitol in order to overturn a free and fair election. By any measure, that’s a worse crime than simple murder, especially since both Trump supporters and police officers died in the aftermath. Yet only a small scattering of Republicans jumped ship.

Since the Trump era that started in 2015, he has repeatedly demonstrated that the party is behind him not matter what. There is no red line, no lie or crime, that could shake his hold. He can trash former party heroes such as John McCain to the cheering of Republican crowds. His quondam critics in the party had to go through a humiliating ritual where they listened to Trump fling mud at them—and sometimes their family members—after which they usually came crawling to kiss Trump’s ring (to phrase the matter politely). This was the fate of Lindsey Graham, Ted Cruz, Nikki Haley, Marco Rubio, and Ron DeSantis. Those GOP critics who remain steadfast found they had no future in the party (the fate of the Never Trumpers, as well as Liz Cheney and Mitt Romney).

The GOP convention in Milwaukee last week was a gaudy display of the Trump cult in action, with ordinary GOP members wearing fake bandages on their ears in tribute to their leader’s supposed martyrdom, as if it were akin to Jesus Christ’s suffering on the cross. Franklin Graham, the tawdry and bigoted son of a the great evangelist Billy Graham, spoke of how Trump “rose from that platform” after his brush with death, a blasphemous evocation of the resurrection Christians see as the central event in their cosmology. During the convention there were noticeably few invocations of the great party leaders of the past: Abraham Lincoln, Ulysses Grant, Theodore Roosevelt, Dwight Eisenhower, and Ronald Reagan. Living Republican presidential candidates (George W. Bush, Mitt Romney) were likewise nowhere to be seen. Instead, it was all Trump all the time, with Trump’s daughter-in-law Lara Trump running the Republican National Committee.

The best explanation for Trump’s death grip on the GOP is the theory advanced by political scientists Daniel Scholzman and Sam Rosenfeld, who argue in their recent book The Hollow Parties that thanks to reforms in the primary system in the 1970s, American political parties lack social cohesiveness and are instead the vehicles of whichever personal faction wins the nomination.

This thesis is obviously true of the Republicans, who are manifestly now little more than another branding exercise by Trump, in the glorious tradition of Trump Magazine, Trump Steaks, and Trump University.

The drama over the last few weeks over Joe Biden’s fitness to serve another term was an interesting test case that showed that the Democrats, for all their faults, are much less hollowed out than the Republicans. To be sure, the core problem arose from the fact that a few personal factions—led by Barack Obama and Bill and Hillary Clinton, as well as Biden—have played an outsize role in the party. It was Obama in 2016 who made the fateful decision to push for Clinton as his successor, discouraging other rivals (including, to his lasting bitterness, Joe Biden). In 2020, Obama shifted gear and threw his support to Biden at a crucial moment, right before Super Tuesday, which again cleared the field, this time with a view toward stopping Bernie Sanders’s robust insurgent campaign. As party standard-bearer, Biden enjoyed the usual deference, which meant that when he made the unwise decision to run again in 2023, no serious mainstream candidate challenged him. Again, the field was cleared.

But the fateful debate of June 27, 2024, ended the conspiracy of silence around Biden’s visible decline.

At first, as I and others noted, Biden took the Trumpian tack of demanding personal loyalty above all else. He demonized critics as antidemocratic elites. He disregarded the advice of party elders such as Barack Obama, Nancy Pelosi, Chuck Schumer, and Hakeem Jeffries. He insisted that he alone had a special talent for leadership that could defeat Trump and preserve alliances such as NATO. Like Trump, Biden seemed to be toying with a Samson Option of threatening to destroy the party if he didn’t get his way.