The poll was completed on Tuesday, the day Biden formally announced his bid for reelection in the 2024 presidential race, and released on Thursday.
The president's approval rating has fallen among Democrats and Republicans, but has particularly fallen with Independent voters - down nine points to 31% from February, a report on the poll said.
Biden's approval decreased by six points since March and one of the main reasons is the Americans' recognition of a declining US economy, the report said.
While 75% of voters see the economy as getting worse, only 16% of voters said they believe the economy is "good" or "excellent," the release said.