Washington D.C., Jan. 18 -- Senior Republican Senator Lindsey Graham slammed US President Donald Trump and Speaker Nancy Pelosi's "sophomoric" back and forth, which recently saw Trump postponing Pelosi's official travel to Brussels, Afghanistan, and Egypt.

Trump's move on Thursday comes after Pelosi wrote to the President recommending a "delay" in the State of the Union address that is scheduled for January 29 or sending in his address to the Congress "in writing".

"One sophomoric response does not deserve another. Speaker Pelosi's threat to cancel the State of the Union is very irresponsible and blatantly political," Graham tweeted on Thursday (local time).

Labelling Trump's move as "inappropriate", Graham further said, "President Trump...