U.S. President Donald Trump talks to reporters as National Security Advisor John Bolton looks on during a meeting with Slovakia's Prime Minister Peter Pellegrini in the Oval Office at the White House in Washington, U.S., May 3, 2019. REUTERS/Jonathan Ernst

WASHINGTON (Reuters) - President Donald Trump told his then-national security adviser in August that he wanted to continue freezing $391 million in security aid to Ukraine until officials there helped with investigations into Democrats, including presidential rival Joe Biden, the New York Times reported on Sunday.

Trump’s statement was described by former White House national security adviser John Bolton in an unpublished manuscript by the conservative Republican foreign policy specialist, the newspaper reported, citing a description of the text from multiple people.

The White House did not immediately respond to a request for comment, nor did Jay Sekulow, who is helping lead Trump’s defense in his impeachment trial in the U.S. Senate. Charles Cooper, a lawyer representing Bolton, did not respond to a request for comment.

Bolton’s assertion could undercut one of the primary defenses made by Trump and his allies amid the impeachment inquiry - that the hold on aid was unrelated to any desire to see Ukraine launch investigations into political opponents, including Biden, whose son Hunter was director of a Ukrainian energy company during his father’s time as vice president.

According to the Times, Trump was pressed for weeks by senior aides, including Bolton, Secretary of State Mike Pompeo and Defense Secretary Mark Esper to release the aid, which had been appropriated by Congress.

But in an August 2019 discussion with Bolton, Trump said he preferred sending no aid to Ukraine until officials there turned over all materials they had about the investigation that involved Biden, as well as Hillary Clinton backers in Ukraine.

The White House has directed Bolton and other administration officials not to cooperate with the impeachment probe, although Bolton has said he would testify on the matter if subpoenaed.

The Senate is hearing arguments for removing Trump from office on charges of abuse of power and obstruction of Congress stemming from the Republican president’s dealings with Ukraine. But it is not clear whether there will be sufficient support among senators to call for additional witnesses and evidence. The House did not receive testimony from Bolton.