For Biden, Another Trump Nomination Presents Opportunity — and Great Risk

To be clear, no one in President Biden’s White House would ever root for Donald J. Trump. To a person, they consider him an existential threat to the nation. But as they watched Mr. Trump open the contest for the Republican presidential nomination with a romp through Iowa, they also saw something else: a pathway to a second term.

Mr. Biden’s best chance of winning re-election in the fall, in their view, is a rematch against Mr. Trump. The former president is so toxic, so polarizing that his presence on the November ballot, as Mr. Biden’s advisers see it, would be the most powerful incentive possible to lure disaffected Democrats and independents back into the camp of the poll-challenged president.

And so, some Democrats felt a little torn this week as the Republican race got underway. None of them would cry if Mr. Trump were taken down by someone like former Gov. Nikki Haley of South Carolina, who has one shot in New Hampshire next week to make it a race. Whatever Ms. Haley’s flaws, and Democrats see many, they do not believe she would pose the same danger to democracy that Mr. Trump does.

But if she won the Republican nomination, she might pose a bigger danger to Mr. Biden.

The paradox recalls 2016, when many Democrats were not unhappy when Mr. Trump won the Republican nomination, on the theory that the country would never elect a bumptious reality-television star who specialized in racist appeals and insult politics. Burned once, they are not so certain this time, but Democrats are banking on the hope that the country would not take back a defeated president who inspired a violent mob to help him keep power and has been charged with more felonies than Al Capone.