Sen. Mitt Romney (R-UT) on Monday became the first Republican senator to state that he would like John Bolton, former White House national security advisor, to testify at the Senate impeachment trial if subpoenaed.

“I would like to be able to hear from John Bolton. What the process is to make that happen, I don’t have an answer for you,” Romney told reporters on Capitol Hill when asked whether he would be open to hearing from Bolton.

In a posted statement, Bolton said that if called to do so at a Senate trial, “I am prepared to testify.”

As a key adviser to Trump, Bolton was close to the president’s dealings with Ukraine. The House of Representatives last month charged Trump with two articles of impeachment stemming from an alleged effort to pressure the Eastern European nation into launching a politically motivated investigation of Democrat presidential candidate Joe Biden.

Bolton said during the impeachment hearings he would not testify before the House Intelligence Committee unless he was first subpoenaed by the committee and then ordered by a judge to defy Trump’s wishes by appearing before Congress.

The legal and constitutional struggle over Bolton’s possible House testimony went unresolved, he noted in his statement. Bolton said:

The House has concluded its constitutional responsibility by adopting articles of impeachment related to the Ukraine matter. It now falls to the Senate to fulfill its constitutional obligation to try impeachments, and it does not appear possible that a final judicial resolution of the still-unanswered constitutional questions can be obtained before the Senate acts. Accordingly, since my testimony is once again at issue, I have had to resolve the serious competing issues as best I could, based on careful consideration and study. I have concluded that, if the Senate issues a subpoena for my testimony, I am prepared to testify.

Bolton’s statement comes after Senate Majority Leader Mitch McConnell (R-KY) reaffirmed he has no plans to invite four current and former White House officials to testify as part of the trial, despite demands from his minority counterpart, Sen. Chuck Schumer (D-NY). House Speaker Nancy Pelosi (D-CA) has refused to send the impeachment articles to the Senate, claiming those on Schumer’s witness list must be heard to ensure a “fair” trial.

“We’ve heard it claimed that the same House Democrats who botched their own process should get to reach over here into the Senate and dictate our process,” McConnell said in a blistering floor speech last week.

The Republican added:

Let me clarify Senate rules and Senate history for those who may be confused. First, about this fantasy that the Speaker of the House will get to hand-design the trial proceedings in the Senate, that’s obviously a non-starter.

“The House went ahead without witnesses, and they didn’t pursue the witnesses in court,” he has said of the request. “They just blew right through that and accused the president of doing something improper by simply invoking executive privilege, which every president has done.”

The UPI contributed to this report.