Two of rock's most politically mouthy performers, Steve Earle and Rage Against the Machine guitarist Tom Morello, will perform a Labor Day concert on Harriet Island in St. Paul during the Republican National Convention.

The pair -- along with Earle's country-singer wife Allison Moorer -- have committed to appearances at the Service Employees International Union's Labor Day Festival, a three-day event just across the river from Xcel Energy Center, where the convention will be based.

A union representing 2 million workers nationwide, such as janitors and security officers, SEIU has also confirmed that former Democratic presidential nominee Sen. John Edwards will appear at its event.

A press release from Earle's and Morello's management office also hints that "friends" might join them. Morello recently recorded a song with Bruce Springsteen and helmed the Justice Tour this spring, joined by members of the Red Hot Chili Peppers and System of a Down. He has worked with SEIU on previous occasions.

Although a consultant for the union downplayed the event's political edge, Earle likely will not have kind words for the Republicans. The country-rocker made waves in 2002 with his post-9/11 album "Jerusalem" and has long stumped for labor-union issues.

"I lived in New York in 2004 during the summer of the Republican convention there, basically so I could [mess] with the Republicans," he told the Star Tribune before a Minneapolis concert in March.

Other musicians are lining up more openly protest-themed events. Members of the Honeydogs and Semisonic are organizing a Sept. 2 outdoor concert called ProVention at Midway Stadium in St. Paul. A musical fundraiser for Sen. Barack Obama called Eight Is Enough will take place Aug. 27 at the Turf Club in St. Paul with Minnesota rock and hip-hop acts such as Low, P.O.S. and Tapes 'N Tapes.

Some well-known performers are confirmed to play more Republican-friendly events during the convention. They include Sammy Hagar and LeAnn Rimes, who will perform for private parties at First Avenue and Trocaderos in Minneapolis, respectively.

Chris Riemenschneider • 612-673-4658