So, you didn't get tickets to Friday night's presidential debate at Wash. U.? Who cares! A more interesting political rally takes place Saturday when Mexican Elvis impersonator El Vez brings his El Camino motorcade to the Duck Room. Always the punster, El Vez (a.k.a. Robert Lopez) has been putting his Latin spin on contemporary music for nearly two decades with albums such as Graciasland and the holiday classic Sno-Way Jose. This time around the artist is on the campaign trail, touring under the banner of El Vez 4 Prez. But before you cast him off as a south-of-the-border Weird Al Yankovic, know that, before striking out on his own, El Vez had a reputable past playing in the Los Angeles punk band the Zeros. Saturday's show promises to be a kaleidoscope of audio and visual treats as El Vez and his lovely background singers, the El Vettes, go through more songs and costumes than Bush and Kerry have votes. The tunes range from twists on Presley and James Brown to remakes of R.E.M. and Beastie Boys songs, with several ditties often sampled onto one song. Like a Tex-Mex platter, the music is less than authentic but has enough zing -- and cheese -- to render it thoroughly satisfying.