A new poll says public approval of U.S. President Donald Trump has dropped to its lowest level since he was inaugurated, with the drop in confidence centered among Republican voters.

A Reuters/Ipsos poll released Friday indicates only 38 percent of U.S. adults now approve of the president, while 56 percent said they disapprove of his performance. The remaining 6 percent said they had "mixed feelings" about the president.

The poll of nearly 2,000 people was taken May 14-18, a week that saw one stunning development after another. On Monday, media reported that Trump had shared classified information with Russian officials; on Tuesday, it was revealed that fired FBI Director James Comey had expressed concern that the president was pressuring Comey to stop investigating his campaign ties to Russia.

Then FBI Director Robert Mueller testifies on Capi Then FBI Director Robert Mueller testifies on Capitol Hill in Washington, June 19, 2013, before the Senate Judiciary Committee. Then FBI Director Robert Mueller testifies on Capitol Hill in Washington, June 19, 2013, before the Senate Judiciary Committee.

By Wednesday, the Justice Department had appointed former FBI Director Robert Mueller to oversee an independent probe of possible ties between the Trump campaign and Russia. And by Thursday, the final day of the poll, Trump had declared efforts to investigate him a “witch hunt.” He said no politician in history had been treated “worse or more unfairly.”

The roller coaster of a week sent Trump's disapproval numbers among Republicans from 16 percent last week to 23 percent this week. Reuters reports that the rise in disapproval among the president's base seems to be the reason his numbers are now at their lowest point.