The poll was conducted from October 2-23.
"President Joe Biden’s job approval rating among Democrats has tumbled 11 percentage points in the past month to 75%, the worst reading of his presidency from his own party. This drop has pushed his overall approval rating down four points to 37%, matching his personal low," the pollster said in the publication of results on Thursday.
The Democrat president's rating has also declined among independents — to 35% from 39% — and remained the same among the Republicans at 5%.
Biden's approval rating last fell to 37% in April, shortly before he officially announced his bid for reelection in the 2024 vote.
Gallup gave Biden's stance on the Gaza Strip conflict as a background to the results of its poll, saying his public pledge of unequivocal support for Israel prompted criticism from some Democrats who believe he should do more for the Palestinians.