The tracking poll from the generally right-leaning Rasmussen Reports, a survey often cited by the president on Twitter, found Trump's approval rating had fallen 2 percentage points over the weekend, to 48 percent.
The poll says that 36 percent of Americans polled approve of President Trump's job performance, while 57 percent disapprove. More than one-third of the respondents said Trump's treatment of the investigation lowered their opinion of him.
Seventy-two percent of Republican respondents to the poll approved of Trump's job performance, while just 9 percent of Democratic respondents approved.
CBS News noted that more than half of Republicans call the investigation a political distraction that should be put aside.
The latest poll has a margin of error of 4 percentage points.
This poll was conducted by telephone June 15-18, 2017 among a random sample of 1,117 adults nationwide.
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Trump's support among Republicans might have been a factor in the drop. Those beliefs cause them to back the President even more.
According to The Washington Post, with the increasing questions regarding how Trump is handling the investigation of the Russian involvement in the 2016 elections, he needs all the support that he can get to make the next few months of his presidency a bit more comfortable. The poll comes on the heels of Senate testimony from Comey and Attorney General Jeff Sessions, as well as the investigation into Russian Federation and alleged collusion with the Trump campaign.
Almost two-thirds of the people surveyed by CBS agree that Trump is more interested in protecting himself than protecting the USA from Russian interference, which only 30 percent believe he values more.
Trump scored better on his handling of several domestic matters, though he failed to earn more than 50 percent approval on any of them.
Most Americans (56 percent) believe that the special counsel's investigation will be impartial, rejecting any assertions to the contrary, and think that the president should not do anything to try to stop it.