Sen. Jeff Flake says he won't be able to say whether he'd support President Donald Trump's border wall until he knows whether the president wants to build a brick-and-mortar structure or instead erect a combination of fencing and other barriers.
The president threatened earlier this week at a rally in Phoenix to shut down the federal government unless the gridlocked Congress agrees to build a border wall.
Flake questioned the wisdom of constructing a wall in a landscape that includes flat desert, rolling hills, canyons, mountains and waterways - all of which present unique challenges.
Trump has recently criticized Flake and expressed support for his primary challenger.
Flake commented about Trump's call for a wall after holding a Senate subcommittee hearing in Phoenix on an unrelated subject.