Major gaffe overshadows appearance at Univison forum.

Obama has learned something during his presidency: You can’t change Washington from the inside.

“The most important lesson I’ve learned is that you can’t change Washington from the inside,” he told a Univision forum Thursday. “You can only change it from the outside.”

The remark immediately set off the political media on Twitter.

“(This) is perhaps Obama’s worst gaffe since he met Joe the Plumber?” BuzzFeed editor Ben Smith asked on Twitter Thursday afternoon.