Former Oregon state Sen. Chip Shields has contributed $320,000 to the campaign for Measure 26-210, the Metro homeless services tax on the May 19 ballot.

Shields, whose family owns Missouri-based Schaeffer's Specialized Lubricants, has been a generous benefactor to left-wing causes and candidates—including $15,000 to recall state Sen. Chuck Thomsen (R-Hood River) this year—but the Measure 26-210 donations are more than he's given before, making him the largest single contributor to the yes campaign.

"I've always known him as someone who steps up for the underdog," says Angela Martin, the campaign's director. Shields did not respond to a request for comment.

His first donation to the campaign was in March. Martin says Shields contributed more following attack ads from the measure's opponents. Backers have called those attacks lies; both sides have engaged lawyers.