Polish PM Tusk loses bellwether regional election WARSAW (Reuters) - The party of Polish Prime Minister Donald Tusk lost an election for mayor of a provincial city that had been one of his strongholds, a sign of the toll the economic slump is taking on the government's popularity. The city of Elblag, near Poland's Baltic Sea coast, has a population of only 124,000, but it took on nationwide significance after Tusk traveled there several times to campaign for his party's candidate. Jerzy Wilk, of the conservative opposition party Law and Justice, won Sunday's election with 52 percent of the vote, against 48 percent for the candidate from Tusk's Civic Platform party, official results showed. Civic Platform had previously held the mayor's office. "This is a signal that we can win in the country," said Adam Hoffman, a member of parliament with Law and Justice. Polish voters will decide whether to keep Tusk's government when the next parliamentary election takes place in 2015. He has overseen a period of political stability, and investors worry the next government could be more volatile. A survey last month by pollster CBOS showed national support for Civic Platform at 23 percent against 26 percent for Law and Justice. Additional reporting by Karolina Slowikowska; Writing by Christian Lowe; Editing by Mark Heinrich