UPDATE: Here's what Sen. Romney told CNN Tuesday morning in the Senate.

New: Mitt Romney tells CNNs @mkraju that Dems are making a “mistake” by saying that “everything is an outrage.”

He says McConnell changes from Clinton trial rules are “modest” and he won’t be voting today on motions to call for witnesses. — Dana Bash (@DanaBashCNN) January 21, 2020

Original Post

Sen. Mitt Romney (R-UT) is one of a handful of moderate Republicans who is undecided as to whether the Senate should allow more witnesses in the impeachment trial against President Trump. He said he's open to it, as long as they take the vote after opening arguments.

Statement from ?@SenatorRomney? about the opening phase of the Senate impeachment trial #utpol pic.twitter.com/BFW8dJGVEe — Liz Johnson (@LJ0hnson) January 21, 2020

"As I have made clear to my colleagues and the public that the Senate should have the opportunity to decide on witnesses following the opening arguments, as occurred in the Clinton trial," he wrote on Monday night. "The organizing resolution released tonight includes this step, and overall, it aligns closely with the rules package approved 100-0 during the Clinton trial. If attempts are made to vote on witnesses prior to opening arguments, I would oppose those efforts."

However, precedent has gone out the window as of late. So much so that Senate Minority Leader Chuck Schumer is accusing the Republicans of participating in a "cover up" for the White House for being so resistant to more witnesses and the presentation of new documents.

As mentioned, Romney is one of the Republicans on the fence regarding additional witnesses. The other persuadable senators include Susan Collins (ME), Lisa Murkowski (AK), Lamar Alexander (TN), and a few other retiring senators.

Sen. Ted Cruz (R-TX) wasn't totally opposed to additional witnesses, because he reasoned that if the Democrats get their way and call more individuals to the stand, then the Republicans should protest until they get to do the same.

Among the witnesses that the Democrats want to hear from are former National Security Advisor John Bolton, Acting White House Chief of Staff Mick Mulvaney, Senior Adviser to the acting White House Chief of Staff Robert Blair, and Office of Management and Budget official Michael Duffey.

President Trump tweeted that it's "not supposed" to work that way.