WASHINGTON — The U.S. Senate dove right into President Donald Trump’s impeachment trial as Republicans abandoned plans to fit opening arguments into two days but have now rejected Democratic demands for more witnesses.

Trump stated that he wants top aides to testify, but suggested there were “national security” concerns to allow their testimony. Trump said he’d like to see aides, including former national security adviser John Bolton, Secretary of State Mike Pompeo, and acting chief of staff Mick Mulvaney, testify as witnesses.

After one particularly bitter exchange, Roberts intervened, taking the rare step of admonishing both the Democratic House managers prosecuting the case and the White House counsel to “remember where they are.”

With the Republican majority of 53-47, the Senate is not expected to mount the two-thirds vote needed for conviction.