“Unfortunately, when it comes to Trump, the Congress is locked down and will not give him what we’ve given past presidents,” Graham said. “So unfortunately, he’s got to do it on his own, and I support his decision to go that route.”

Graham, a staunch ally of Mr. Trump in the Senate, noted that former Presidents George Bush and Barack Obama sent troops to the border. He argued that many in Congress only oppose the wall because Mr. Trump is the person proposing it.

Graham also discussed Mr. Trump’s comment Friday that he “didn’t need to” call the national emergency, but he did so because he would “rather do it much faster.” Graham said that this comment did not open the national emergency to legal challenges.