Voting is scheduled to begin at 6 a.m. Tuesday on tentative contract agreements between 12,000 nurses and 14 Twin Cities hospitals, but the results might not be known until early Wednesday, union officials said. The Minnesota Nurses Association (MNA) said it will not begin counting the votes until after the polls close at 10 p.m., and the final tally is not expected until midnight or 1 a.m. A strike, which had been scheduled to begin Tuesday morning, was called off last week when negotiators for both sides reached the agreement. A simple majority of voting union members is needed to ratify.