Sen. Lindsey Graham (R-S.C.) criticized President Trump on Thursday for canceling House Speaker Nancy Pelosi's (D-Calif.) overseas visit to troops in Afghanistan, calling the move "inappropriate."

Graham also criticized Pelosi for "playing politics with the State of the Union." Pelosi on Wednesday sent a letter to Trump requesting that he agree to postpone the Jan. 29 address or deliver it in writing if the partial government shutdown has not ended.

The South Carolina Republican, an ally of Trump's who has also criticized the president from time to time, called on both Trump and Pelosi to "find the same desire to work for common goals as those who serve our nation in uniform and other capacities."

Trump in a letter to Pelosi on Thursday wrote that he was canceling a trip she and other lawmakers were set to take to Brussels, Egypt and Afghanistan. Trump wrote that Pelosi should remain in Washington to negotiate with him on the shutdown, which is now in its 27th day.

The letter was Trump's first response to Pelosi's proposal to postpone the State of the Union address.

Trump's letter canceling the trip suggests he will refuse to provide military transportation for the congressional trip, which would have included a stop in a war zone.

"Obviously, if you would like to make your journey by flying commercial, that would certainly be your prerogative," Trump wrote to Pelosi.

Former Secretary of State John Kerry slammed Trump on Twitter for describing the trip in the letter as "a public relations event."

"The President of the United States just compared visiting our troops in a war zone to a 'public relations event,' " Kerry tweeted. "Another sad day for our nation when that's how the Commander in Chief sees such a visit."

Kerry previously criticized Trump in November for canceling a visit to a French World War I memorial because of bad weather.