The Connecticut Conference of Municipalities is calling on state leaders to oppose a Senate bill expanding the power and reach of public-sector labor unions, arguing the proposal would place new burdens on many towns and cities and complicate the relationship between municipal employers and their workers. The legislation, known as SB 908, would require public employers to supply unions with employees’ contact information, give union officials access to new employee orientations, and allow public employees and retirees to authorize deductions from their salaries or retirement payments to pay union dues. Co-sponsored by Senate President Pro Tem Martin M. Looney, D-New Haven, and Sen. Julie Kushner, D-Danbury, the bill was recently passed out of the Labor Committee and added to the Senate’s calendar.