Sen. Susan Collins (R-Maine) ousted Mitch McConnell (R-Kentucky) as the Senator with the worst approval rate, a Morning Consult poll tracker released quarterly on Thursday showed.

The poll found that Collins’s net approval rating dropped 10 points in Maine since the end of September, likely due to the intense scrutiny she has been under since the House launched the impeachment inquiry into President Donald Trump.

Now she holds a 52% disproval rate and a 42% approval rate.

The second least popular senator, McConnell, registered a lower approval rating, 37%, but a better disproval rate at 50%.

The ratings are calculated “by total approval and total disapproval, with net approval (approval minus disapproval) serving as the tiebreaker.”

The most popular senator according to the poll is presidential candidate Bernie Sanders (I-Vermont) who has recently surged in polls about the 2020 Democratic nomination.

His fellow Senator candidate, Elizabeth Warren (D-Massachusetts), falls on the other side of the spectrum. She is listed as the ninth most unpopular senator, with an approval rate of 50% and disproval rate of 40%.

The poll is based on surveying 5,000 registered voters about their senators each day. While the margin of error for each lawmaker is different, Collins’s is +/-2%.

Kevin Kelley, a spokesman for Collins’s campaign, claimed the poll was not credible.

“This is an online poll that has little credibility. We are confident that it does not reflect reality, and Senator Collins remains focused on the job that Mainers elected her to do,” Kelley told The Hill.

Collins, who is often viewed as a more moderate Republican, has struggled to appease both parties of her constituents. Many Democrats were dismayed when she voted to confirm controversial Brett Kavanaugh to the Supreme Court, and called on her to remain impartial during Trump’s impeachment trial.

She appears to be open to hearing new evidence and testimony, something Democrats are pushing for during the trial.

“For this trial, as was done in 1999, both sides should have the opportunity to state their case and the Senators should have the opportunity to pose questions. Then, the Senate should have an up-or-down vote on whether to subpoena witnesses and documents,” she said.