U.S. Sen. Cory Gardner doesn’t believe the Senate needs to call witnesses in the impeachment trial of President Donald Trump.

The Yuma Republican, who faces a tough re-election fight this November, spoke definitively on the topic for the first time Wednesday.

“I do not believe we need to hear from an 18th witness,” Gardner said in a statement.

“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,” the senator added.

Democrats and a few of Gardner’s Republican colleagues have said John Bolton, a former national security adviser, should testify in the trial. Though impeachment prosecutors have cited evidence and testimony from witnesses called by House investigators, the Senate trial has not had any witnesses.

Last week, Gardner voted to table a subpoena for Bolton and several other witnesses, along with documents from several federal agencies. On Tuesday, the senator told The Denver Post he was still considering whether to vote for witnesses, but reportedly told his Republican colleagues he opposed witnesses.

Among the 10 Democrats hoping to face Gardner in November, news of his opposition to witnesses was met with immediate criticism Wednesday.

“Don’t confuse Cory Gardner with the facts — or with a moderate,” said Andrew Romanoff. “He’s loyal to a fault, but not to Colorado.”

Trish Zornio said in an email to supporters that Gardner “turned his back on the oath he took to be an impartial juror” and made “a mockery of our Constitution and democracy.” Lorena Garcia called Garcia’s decision “shameful.”

“A trial without witnesses and evidence is not a trial at all,” said John Hickenlooper. “It’s a sham.”