Utah Republican Sen. Mitt Romney lost support from Republicans and independents in his home state during the weeks after he called for witnesses in President Trump's Senate impeachment trial, a new poll shows.

The Morning Consult survey found support for Romney, 72, going down after he called for former national security adviser John Bolton to testify at Trump’s impeachment trial, which began on Thursday.

The poll shows the senator’s approval rating falling among Utah Republicans from September through December 2019, and independents also shifted to disapproving of Romney over the quarter.

In the prior quarter, 65% of Utah Republicans supported Romney, and while a majority still do presently, that number sank to 57%.

The numbers are particularly striking for Utah, one of the most Republican states in the country. Romney romped to victory in his 2018 Senate bid and has been considered a local hero of sorts among his fellow Church of Jesus Christ of Latter-day Saints constituents and others.

The Utah Republican senator, however, did gain among Democrats in his state. According to the poll, 46% of Democrats late last year in the fourth quarter approved of the former Massachusetts governor and 2012 Republican presidential nominee. This was a spike of 4 percentage points from several months prior.

Trump was impeached by House Democrats on Dec. 18 for abuse of power and obstruction of Congress over his July 25 phone call with the newly elected Ukrainian president, Volodymyr Zelensky.

Democrats claim Trump pressured Zelensky to dig up political dirt on former Vice President Joe Biden, a leading Democrat vying to take on the president in November 2020.

Following the release of the transcript of the call, Romney described the conversation as “troubling in the extreme.”

Romney's remarks led to further tension with Trump, leading the president to release a video mocking Romney's election loss against President Barack Obama in 2012.

Romney is part of a small group of Republican senators who say they want to hear from Bolton, one of the witnesses Democrats say should testify. Bolton has indicated he would testify if he is subpoenaed.

Morning Consult conducted 494,899 surveys with registered U.S. voters from Oct. 1 through Dec. 31, 2019, to determine the fourth-quarter 2019 popularity ratings for senators. The margin of error was plus or minus 2 percentage points.