On Wednesday afternoon, shortly before he was scheduled to speak to reporters, Mr. Trump rebuked congressional Democrats, who have indicated they aren’t waiting for the president’s guidance on an economic package to help the economy. “Someone needs to tell the Democrats in Congress that CoronaVirus doesn’t care what party you are in. We need to protect ALL Americans!” Mr. Trump wrote on Twitter.

In interviews, a half-dozen Republicans close to the president’s campaign said that his re-election effort had become a political battleship, slow and creaky to turn, unlike the nimble race Mr. Trump ran in 2016. Several advisers worked on Tuesday to persuade Mr. Trump not to let the campaign announce a rally tentatively scheduled for the end of the month in Florida; those advisers ultimately won.

Aides have sent mixed signals about how they plan to approach Mr. Biden, with some wanting to portray him as a 2020 version of Hillary Clinton, and others wanting to try to define him as interchangeable with Mr. Sanders because of some of the progressive stances Mr. Biden has adopted.

Primary results cannot easily be projected onto general elections, but the surge in Democratic turnout so far has not only helped Mr. Biden, it has also illustrated what may be Mr. Trump’s most glaring vulnerability. The former vice president has established a commanding delegate lead in part because of a surge of suburban voters including many from affluent jurisdictions.

In Virginia, North Carolina and Michigan — each a general election battleground — Mr. Biden benefited from a large increase in turnout among moderate voters in the Washington, Charlotte and Detroit suburbs.

In Michigan, for example, over a million and a half voters participated in the Democratic primary Tuesday — up from just over 1.2 million in 2016 there. But it was where the turnout jumped so much that was revealing and, for Mr. Trump, ominous. In affluent Oakland County, Mitt Romney’s boyhood home and an epicenter of the Democrats’ 2018 midterm election gains, turnout went from approximately 180,000 in 2016 to about 260,000 on Tuesday.

Mr. Trump’s team of actual political strategists is small, despite the large staff employed by his campaign, and his campaign manager only recently relocated to Washington, where the headquarters is based. After data leaked early on, information is closely guarded and formal polling is ordered only every few months. On Tuesday, as Mr. Trump sat with advisers in the late morning going over the results of the latest campaign surveys, some of the data was already out of date.