DENVER (CBS4)– Sen. Cory Gardner is among the senators questioning President Donald Trump’s attorneys and house managers in the impeachment trial. The Republican senator from Colorado said he doesn’t believe the Senate needs to hear from new witnesses.

Senator from Colorado Cory Gardner (R-CO) walks outside the Senate chamber during a recess in the impeachment trial against President Donald Trump at the US Capitol on January 28, 2020 in Washington, DC. (Photo by Brendan Smialowski / AFP) (Photo by BRENDAN SMIALOWSKI/AFP via Getty Images)

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“I do not believe we need to hear from an 18th witness. 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,” said Gardner on Wednesday.

Gardner previously had been noncommittal on the subject of more witnesses.

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The Senate has 18 hours to ask all of their questions, in writing. The question of calling more witnesses will not be addressed until Friday, but Senate Majority Leader Mitch McConnell said he doesn’t believe he has enough votes to block witnesses.

Among those witnesses who could be called: former National Security Advisor John Bolton. The White House sent Bolton a letter on Wednesday informing him that he could not publish his book due to classified information.

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The book includes allegations that Trump directly linked aid to Ukraine to a political investigation.