Joe Biden was so pumped America was able to pull out the win in the World Cup on Tuesday -- he straight-up led an ole-fashioned "U-S-A!" chant at a political event!!
POTUS was out in Michigan while the must-win game against Iran was going down in Qatar ... and after the 1-0 contest ended, he grabbed the mic to gloat to the room.
Audio issues missed the first part of his impromptu winners speech -- but it all clicked on just in time to hear him egg on a pro-U.