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As the Senate impeachment trial of President Donald Trump lurches on, there’s more drama stemming from John Bolton’s yet-to-be-released book.

The New York Times reported on Monday that the former national security adviser’s forthcoming book contains his recollection of a conversation with Attorney General William Barr, in which Bolton told Barr that he thought Trump was “effectively granting personal favors” to Chinese President Xi Jinping and Turkish President Recep Erdoğan.

Barr responded by mentioning Justice Department investigations into Turkish and Chinese companies, and told Bolton that Trump’s communications with Erdoğan and Xi had created the appearance that Trump was trying to influence an independent investigation, according to the Times.

In a late-night statement issued following the publication of the story, the Justice Department essentially threw Bolton under the bus and denied everything:

Reached for comment, the White House directed VICE News to the Justice Department's statement.

Previous reporting on Bolton’s manuscript from Monday indicated that Trump told Bolton that military aid to Ukraine was tied to that country’s willingness to investigate Joe and Hunter Biden, a central claim of the impeachment trial. On Monday, Trump said Bolton’s allegations were untrue and that he was saying them “only to sell a book.”

The Trump administration’s attempt to put a lid on this might not be enough. On Monday, following the publication of that Times story, two Republican senators, Susan Collins of Maine and Mitt Romney of Utah, broke with the party line and indicated that they would support calling more witnesses.

If all Democrats vote to call more witnesses—conservative West Virginia Democratic Sen. Joe Manchin, whom the White House is reportedly targeting as a potential acquittal vote, said over the weekend that he would “love to hear” from Mick Mulvaney and Bolton—it would take just two more Republican votes to make the subpoena a reality.

The Times reported Tuesday morning that multiple GOP senators, including Pat Toomey of Pennsylvania and Lisa Murkowski of Alaska, had expressed openness to having Bolton testify. Other top Republicans, however, continued to hold their ground, with some going after Bolton himself.

"We'll still vote on Friday on if additional witnesses will be required," Texas Sen. John Cornyn told Fox News on Monday. Asked what would change about the trial if additional witnesses such as Bolton were called to testify, Cornyn responded: "It would go on forever and ever."