The Trump campaign has recently undertaken a multimillion-dollar advertising effort in those two states as well as Arizona in hopes of improving his standing, while also shaking up his political operation and turning new attention to states like Georgia that were once considered reliably Republican. In private, Mr. Trump has expressed concern that his campaign is not battle-ready for the general election, while Republicans are concerned about whether the president can emerge in a strong position from the national crises battering the country…

In private polling conducted by Mr. Trump’s campaign, the president is now well behind Mr. Biden, according to people briefed on the most recent round of results. Multiple public surveys this week have found Mr. Trump trailing Mr. Biden, the former vice president, by double-digit margins, including a Monmouth University poll published on Wednesday that showed Mr. Biden ahead by 11 percentage points…

Polls released on Wednesday show another troubling sign for Mr. Trump: His numbers have flagged recently among white voters, driven by a continued erosion of support from those with college degrees. The latest Monmouth survey found Mr. Trump with the support of just 52 percent of white voters nationwide — five percentage points lower than his share in 2016, according to exit polls.

There are also at least faint signs of renewed discomfort with Mr. Trump among a sliver of suburban Republican primary voters who could doom him altogether if they were to shift to Mr. Biden in November.