Graham: Dems 'trying to destroy Donald Trump'
His comments come as the Republican-controlled U.S. Senate hears opening arguments in Trump's impeachment trial, beginning several days of argument on whether to remove Trump from office.
In Davos, Switzerland, Trump said allowing current and former top administration officials such as John Bolton to testify at the trial would present national security concerns.
In a 13-hour battle over trial rules that lasted until the wee hours of Wednesday, Republican senators rejected requests for subpoenas seeking the testimony of Bolton, Trump's former national security adviser, and three White House officials.
That battle is likely to resume next week.
Trump was impeached last month by the Democratic-run House of Representatives on charges of abuse of power and obstruction of Congress for pressuring Ukraine to investigate former Vice President Joe Biden, a Democratic political rival, and impeding a congressional inquiry into the matter.
The president denies any wrongdoing.
