Only 38% of poll respondents said they approved of Biden's performance as president, down from 40% in December.
A separate Reuters/Ipsos poll earlier this month showed Trump with a six percentage-point lead in that matchup.
They are pressing ahead with an effort to impeach Biden's top border official, Homeland Security Secretary Alejandro Majorkas.
The economy remained Americans' overall top concern, cited by 22% of poll respondents, as they have struggled with inflation and other aftershocks of the COVID-19 pandemic.
It has a margin of error of plus or minus 3.3 percentage points for all respondents, 6.4 points for just Republicans and 6.1 points for just Democrats.
Persons:
Andy Sullivan WASHINGTON, Joe Biden's, Donald Trump, Biden's, Alejandro Majorkas, Andy Sullivan, Scott Malone, Jonathan Oatis
Organizations:
Democrat, Reuters, Republican, Trump, Republicans, Homeland
Locations:
Mexico, Alejandro Majorkas . U.S