Republicans pressed their offensive against the Democratic-led impeachment inquiry targeting President Donald Trump on Thursday with plans for a Senate resolution calling the investigation illegitimate while the White House lauded lawmakers in his party who stormed into a high-security room and interrupted testimony.

The House of Representatives is examining whether there are grounds to impeach Trump over his request in a July telephone call to Ukrainian President Volodymyr Zelenskiy to investigate a domestic political rival, Joe Biden. The former vice president is a leading contender for the Democratic nomination to face Republican Trump in the 2020 presidential election.

Trump on Monday called on Republicans to "get tougher" in fighting the impeachment inquiry. His ally, Sen. Lindsey Graham, who on Tuesday agreed with Trump that the president was the victim of a "lynching" by Democrats, was scheduled to announce his resolution later on Thursday. Graham's office described the measure as a resolution condemning the "closed-door, illegitimate impeachment inquiry."