Brett Loper, a top aide to House Speaker John Boehner, is leaving the Hill to head up the Washington office of American Express.

The loss is a blow to Boehner (R-Ohio), who relied on Loper to help navigate tricky policy issues, particularly budget battles — and with upcoming action expected on immigration and the debt limit, no doubt he’ll be particularly missed.

“Brett has been an invaluable asset, not just to my office, but also the entire House Republican team,”Boehner said in a statement.

Loper is a longtime GOP aide, whose resume includes a stint in the office of former House majority leader Tom DeLay (R-Tex.). He’s spent time off the Hill, too, including jobs at Fannie Mae and AdvaMed, the Advanced Medical Technology Association.

Boehner did not immediately announce Loper’s replacement.