House Co-Speaker Arnie Roblan, a Coos Bay Democrat who represents northwest Douglas County, is giving up his high position in a bid for the 5th District Senate seat. He’s opposed by North Bend Republican Scott Roberts, a 45-year-old oral surgeon. The race is one of three legislative elections in which Douglas County voters form a minority of the electorate. In the 1st House District, which includes southwest Douglas County as well as parts of Curry, Josephine and Coos counties. Rep. Wayne Krieger, R-Gold Beach, is being challenged by Brookings Democrat Jim Klahr. In the 9th House District, Coos Bay Democrat …