Former national security adviser John Bolton released a statement on Monday morning saying he's prepared to testify in the Trump impeachment trial before the U.S. Senate.

Bolton's statement in full:

During the present impeachment controversy, I have tried to meet my obligations both as a citizen and as former National Security Advisor. My colleague, Dr. Charles Kupperman, faced with a House committee subpoena on the one hand, and a Presidential directive not to testify on the other, sought final resolution of this Constitutional conflict from the Federal judiciary. After my counsel informed the House committee that I too would seek judicial resolution of these Constitutional issues, the committee chose not to subpoena me. Nevertheless, I publicly resolved to be guided by the outcome of Dr. Kupperman's case.

But both the President and the House of Representatives opposed his effort on jurisdictional grounds, and each other on the merits. The House committee went so far as to withdraw its subpoena to Dr. Kupperman in a deliberate attempt to moot the case and deprive the court of jurisdiction. Judge Richard Leon, in a carefully reasoned opinion on December 30, held Dr. Kupperman's case to be moot, and therefore did not reach the separation-of-powers issues.

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.

The NYT reports: “Mr. Bolton declined to say on Monday precisely what he would be willing to tell Congress. But former White House officials and people close to Mr. Bolton have indicated that his testimony would likely be damning to Mr. Trump and put additional pressure on moderate Republicans to consider convicting him. That could fundamentally change the dynamics around the impeachment trial in the Senate, where a two-thirds vote — 67 senators — is needed to remove Mr. Trump. Democrats, the minority party, control 45 seats.”