President Trump is gaining ground in the 2020 presidential race against Democratic challenger Joseph R. Biden in a new national poll of registered voters from CNN published on Sunday night.

Mr. Biden, the former vice president, leads Mr. Trump by 4 percentage points, 50-46, in the national survey conducted from Aug. 12-15 by SSRS for CNN. Mr. Biden has lost significant ground since June when he led Mr. Trump by 14 percentage points, 55-41.

“The movement in the poll among voters nationwide since June is concentrated among men (they split about evenly in June, but now 56% back Trump, 40% Biden), those between the ages of 35 and 64 (they tilt toward Trump now, but were Biden-leaning in June), and independents (in June, Biden held a 52% to 41% lead, but now it’s a near even 46% Biden to 45% Trump divide),” wrote Jennifer Agiesta, CNN polling director.

Mr. Trump and Mr. Biden are also statistically tied across 15 battleground states with Mr. Biden edging Mr. Trump 49% to 48%. Mr. Trump won 10 of the 15 states CNN has deemed battleground territory in 2020, and Ms. Agiesta wrote that the 15 states “represent a more Republican-leaning playing field than the nation as a whole” in 2020.

The SSRS poll for CNN surveyed 1,108 respondents by telephone, via both landlines and cellphones, including 987 registered voters with a 4 percentage point margin of error. The poll surveyed 636 registered voters in the 15 battleground states with a 5 percentage point margin of error.