White House pool photo
The slogan on the hat references President Donald Trump's signature campaign pledge to build a wall along the US-Mexico border to help curb illegal immigration.
A White House pool report identified the man as Fredy Burgos, a Virginia Republican.
Late last month, companies began constructing prototypes for the promised wall. Earlier this week, the House Homeland Security Committee approved border security legislation that includes $10 billion in funding for a border wall.
It will now head to the House floor as part of a debate on legislation to extend the Deferred Action for Childhood Arrivals (DACA) program, which Trump announced last month his administration would phase out over six months while giving Congress a window to work out a potential permanent solution.
Democrats have vowed to oppose any wall funding as part of a deal.