Former national security adviser John Bolton, highly sought by Democrats as an impeachment witness, said Monday that he is prepared to testify in a Senate trial if a subpoena is issued — a move that could be damaging to President Trump.

The development came as Trump called for a quick end to the impeachment process and congressional Republicans stepped up pressure on House Speaker Nancy Pelosi (D-Calif.) to transmit articles to the Senate, allowing a trial to begin in the chamber. Pelosi has been holding on to the documents as Democrats seek guarantees about the scope of a Senate trial, including witnesses.

The crux of the Democrats’ case is the allegation that Trump tried to leverage a White House meeting and military aid, sought by Ukraine to combat Russian military aggression, to pressure Ukrainian President Volodymyr Zelensky to launch an investigation of former vice president Joe Biden and his son Hunter Biden, as well as a probe of an unfounded theory that Kyiv conspired with Democrats to interfere in the 2016 presidential election.

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