Biden’s advantage is the biggest recorded by the Reuters/Ipsos poll since Democrats began their state nominating contests this year to pick their party’s nominee to challenge Trump in November. A similar CNN poll from earlier this month showed Biden with a 14-point lead over Trump among registered voters.

The Reuters/Ipsos poll also showed that 57% of U.S. adults disapproved of Trump’s performance in office, while just 38% approved, marking Trump’s lowest approval rating since November, when Congress was conducting its impeachment inquiry into the Republican president.

In a clear warning sign for Trump, his own support base appears to be eroding. Republicans’ net approval of Trump is down 13 points from March to June, declining every month in that span.