The accordion player is a fixture in the historical center of Slovenia's capital, Ljubljana. Whatever the season, he perches on a chair in Preseren Square — sporting traditional costume and a feather in his hat — and runs through a limited repertoire of traditional tunes. In the collection box at his feet, a sign reading "Slovenian Music" points patrons toward the CDs he offers for sale. In an odd turn of events, the accordion — and the traditional music played on it — has become a symbol for Slovenia's main opposition party, the right-wing Slovenian Democratic Party (SDS). With a parliamentary election taking place on March 22, it's hard to turn a corner in Ljubljana without running into a campaign poster featuring a winsome young boy posing with the instrument in his hands. "Vote SDS, so your grandson will still sing Slovenian songs," reads the accompanying slogan.…