2024 at a Crossroads

The 2024 presidential race hurtled toward a consequential crossroads on Thursday, as top Democrats ratcheted up pressure to deny President Biden his party’s nomination while bullish Republicans prepared for a balloon drop to formally select a bandaged Donald J. Trump as their standard-bearer.

An extraordinary three weeks in American politics took another surprise turn, after the White House announced on Wednesday that Mr. Biden had contracted Covid, forcing the president into physical isolation just as his presidential candidacy hung in the balance.

A race that not long ago seemed a staid rematch came to a dramatic pivot point after a head-spinning series of events: a disastrous debate late last month that made longstanding questions about Mr. Biden’s age unavoidable, and then a shocking attempted assassination of Mr. Trump less than 48 hours before the start of the Republican National Convention in Milwaukee.

For a fleeting few hours on Wednesday, the two presidents presented starkly dueling images that fed into the very story line Republicans were unspooling at their convention — that Mr. Trump was strong and Mr. Biden was weak. One was flying to his beach house on Air Force One to enter seclusion as his party fractured around him; the other was welcomed as a wounded hero by thousands of cheering supporters, some of whom bandaged their ears in a show of solidarity.

“Teddy Roosevelt’s man in the arena has a name, and it’s Donald J. Trump,” Donald Trump Jr. told the delegates, invoking the attempted assassination of Mr. Roosevelt in Milwaukee in 1912 while he was campaigning to return to the White House. “There is tough. Then there is Trump tough.”

Two presidents have not run against each other since that race in 1912. And