Biden to Describe Trump as ‘Existential Threat’ as They Circle Each Other in Iowa

Up to this point, Mr. Biden has largely resisted responding to Mr. Trump’s individual broadsides, insisting repeatedly that he wants to avoid a “mud-wrestling match” with the president and often ignoring shouted questions from reporters about Mr. Trump’s remarks.

But that hardly means Mr. Biden avoids discussing Mr. Trump. In fact, more than most of his rivals for the Democratic presidential nomination, Mr. Biden is centering his campaign squarely on defeating the president, calling his administration an “aberration.” It’s a point of emphasis sharply at odds with several of his Democratic opponents, who believe Trumpism has redefined the Republican Party and say the country needs bigger, structural change that goes beyond defeating one man.

At every turn, Mr. Biden is seeking to keep the focus on a possible general election matchup between himself and Mr. Trump. He has recently visited Pennsylvania and Ohio, important general election swing states, arguing that he is able to connect in the industrial Midwest and torching Mr. Trump’s leadership approach.

He has generally avoided responding to fellow Democrats, even as his opponents ramp up their critiques of him. One exception came Monday, when he implicitly responded to the entrepreneur Andrew Yang, who had criticized him for missing a gathering of Democrats in Iowa over the weekend that drew most of the primary field.

“My granddaughter was graduating,” he said at a fund-raiser. “It was my daughter’s birthday. I would skip inauguration for that.” He is expected to reiterate a version of that message on Tuesday.

Mr. Biden has also begun to roll out policy platforms, including on climate and education, though he has released fewer than many of his rivals so far. But on the campaign trail he often underscores that the first step to achieving any Democratic priority is beating Mr. Trump.

“If you want to know what the first, most important plank in my climate proposal is, beat Trump,” he said at his campaign’s first large-scale rally, held last month in Philadelphia. “Beat Trump, beat Trump.”