Congressional Democrats say John Bolton, Trump’s former national security adviser, must testify in the impeachment trial — after the New York Times reported Sunday evening that the president told Bolton he intended to withhold military aid from Ukraine unless it opened an investigation of the Bidens.

Based on leaks from Bolton’s forthcoming memoir, the Times reported that during a conversation with him last August, Trump linked the delay of nearly $400 million in military aid to the investigations of former vice president Joe Biden and his son Hunter Biden.

White House officials have been fully aware of the contents of Bolton’s book, The Room Where It Happened, since it was submitted for classification review late last year. It is scheduled for publication on March 17.

On Sunday the seven House impeachment managers issued a statement calling the report “explosive” and urged the Senate to call Bolton as a witness in Trump’s trial. Previously, he has said he will testify before the Senate if subpoenaed.

“The Senate trial must seek the full truth and Mr. Bolton has vital information to provide,” said the House managers. “There is no defensible reason to wait until his book is published, when the information he has to offer is critical to the most important decision senators must now make — whether to convict the president of impeachable offenses.”

In a series of midnight tweets, Trump denied telling Bolton about the Ukraine scheme:

I NEVER told John Bolton that the aid to Ukraine was tied to investigations into Democrats, including the Bidens. In fact, he never complained about this at the time of his very public termination. If John Bolton said this, it was only to sell a book.