A Minnesota lawmaker who is a Democratic candidate for Congress has apologized for wagering through an online prediction market that he'd win his party primary. State Sen. Matt Klein, Mendota Heights, issued a statement Wednesday about using $50 of his own money last October to wager on the primary for the 2nd Congressional District seat. The seat is open as the incumbent, Rep. Angie Craig, runs for U.S. Senate. “That was the only wager I have ever made on a predictions market,” Klein said.