Sen. Cory Gardner Cory Scott GardnerMcConnell locks down key GOP votes in Supreme Court fight Will Republicans' rank hypocrisy hinder their rush to replace Ginsburg? Jeff Flake: Republicans 'should hold the same position' on SCOTUS vacancy as 2016 MORE (Colo.), a vulnerable GOP senator up for reelection this year, said Wednesday that he will oppose any effort to call new witnesses as part of President Trump Donald John TrumpBiden leads Trump by 36 points nationally among Latinos: poll Trump dismisses climate change role in fires, says Newsom needs to manage forest better Jimmy Kimmel hits Trump for rallies while hosting Emmy Awards MORE's impeachment trial.

Gardner, in a statement to Colorado Politics, said he did not "believe we need to hear from an 18th witness," referring to individuals called during last year's House impeachment inquiry.

"I have approached every aspect of this grave constitutional duty with the respect and attention required by law, and have reached this decision after carefully weighing the House managers and defense arguments and closely reviewing the evidence from the House, which included well over 100 hours of testimony from 17 witnesses," he added.