Democrats worried about Trump's growing strength

Senate Democrats are privately acknowledging that President Trump will be very tough to beat in November if the economy stays strong and he draws on the substantial advantages of running as an incumbent.

Publicly, Democratic lawmakers are putting on a brave face, but behind closed doors anxiety is mounting over the unraveling of former Vice President Joe Biden’s White House bid and the failure of impeachment to put a dent in Trump’s approval ratings.

One of the chief concerns is that Trump, who has a virtually uncontested path to the...