Midnight Oil's Peter Garrett tried to fit in as a Summerfest party band, examining the half-sauced crowd and joking: "Sometimes too much beer is never enough!"

But Sammy Hagar he ain't.

For the rest of a vibrant show encompassing nearly two decades of hits, the Australian band preferred to embrace its role as the festival's most overtly political performers.

At one point, volunteers even hoisted a banner protesting the Yucca Mountain nuclear waste dump in Nevada as Garrett urged fans to lobby Senators Feingold and Kohl.

For the most part, Midnight Oil's messages were mixed more subtly into their brand of surf punk, in such favorites as "Truganini" (British colonialism), "Golden Age" (materialism) and "The River Runs Red" (environmental degradation, a running theme).

A stripped-down set in the middle of the show cost the band some of its swagger. The notable exception was a blistering "Blue Sky Mine," launched by Garrett's harmonica and sustained by the reliable harmonies and rhythmic backbone of bassist Bones Hillman.

Even those who missed the social commentary were transfixed by the stage presence of Garrett, who remains one of rock's most compelling live performers. The 6-foot-4 frontman, head shaved bald, channels the guitars and drums like a tai chi practitioner plugged into an electrical current.

As the show neared its end, Midnight Oil dedicated its signature anthem, "Beds are Burning," in part to the area's Native Americans. The "Potawatomi Bingo" banner behind the stage would have provided perfect ironic fodder.

Instead, with fans joining the band in chanting "It belongs to them. Let's give it back!" Midnight Oil's music once again did the talking.