2020 presidential candidate Sen. Bernie Sanders on Wednesday weighed in on the impeachment trial and how he feels about being off the campaign trail in order to be present for the trial, in a conversation with the Daily Caller.

“Well, I was disappointed that the Republicans would not support a trial which had witnesses. I’m not, I don’t think I’ve ever heard of a trial where you don’t have witnesses. That was kind of disappointing,” Sanders said to the Daily Caller.

When asked if he wished he was back on the campaign trail Sanders said, “You know, I took my oath of duty and it’s my constitutional responsibility to be here in D.C. for the impeachment trial. I surely wish I would, you know, could be in Iowa and New Hampshire, but it’s the way it is.”

Sanders, as well as Massachusetts Democratic Sen. Elizabeth Warren and Minnesota Democratic Sen. Amy Klobuchar have all had to temporarily abandon the campaign trail, in order to be present for Trump’s impeachment trial in the Senate. (RELATED: Watch Bernie Sanders Try To Use His Phone To Avoid Questions On Fairfax Allegations)

Meanwhile, a group of Republicans also voiced their concerns with the trial on Wednesday, criticizing Democrats for the way they have been handling the impeachment process against Trump. (RELATED: Graham Rips Democrats Over Trump Impeachment Process: ‘I Wouldn’t Cooperate’)

The impeachment trial could potentially be over before Trump’s scheduled State of the Union address, on Feb. 4.