Meanwhile, he has weighed in on candidates considered second tier, as well as those who have yet to enter the race.
Ms. Klobuchar’s snow-blanketed kickoff rally turned into a briefly viral moment that Mr. Trump simply couldn’t pass up, the operative said. His strikes against former Vice President Joseph R. Biden Jr., who has yet to decide whether he will run, appear to be in the workshop phase.
“When I say something that you might think is a gaffe, it’s on purpose; it’s not a gaffe,” Mr. Trump said at a recent off-the-record lunch with network anchors. “When Biden says something dumb, it’s because he’s dumb.”
Rather than individuals, Mr. Trump’s campaign operatives, meanwhile, are hoping to elevate Democratic positions that seem out of step with the mainstream, like a 70 percent top tax rate, abolishing Immigration and Customs Enforcement and questioning American support for Israel.
The only presidential tweet backed by political advice, they said, was Mr. Trump’s broadside against the “Green New Deal,” an ambitious Democratic proposal that seeks to combat climate change by calling for the United States to eliminate additional carbon emissions by 2030.
Brad Parscale, Mr. Trump’s campaign manager, discussed the Green New Deal with Mr. Trump, an aide said, citing it as an example of a vulnerability for Democrats, and a way to brand them as “socialists.”
“I think it is very important for the Democrats to press forward with their Green New Deal,” Mr. Trump wrote on Twitter on Saturday. “It would be great for the so-called ‘Carbon Footprint’ to permanently eliminate all Planes, Cars, Cows, Oil, Gas & the Military — even if no other country would do the same. Brilliant!”