The mayors of 12 Maine cities are asking the state to borrow $85 million that they say will spur development and create jobs in their communities. The Mayors’ Coalition on Jobs and Economic Development said Monday that the bond package would also provide money for downtown improvements, research and development projects, new job training programs through community colleges, improvements to roads, rail lines and walking trails and upgrades to water and sewer systems. Augusta Mayor Bill Stokes says stronger downtowns can help create economic growth and the bond issue would help that happen. The proposed bond package is sponsored through legislation by state Sen. Roger Katz, an Augusta Republican. The coalition includes mayors from Auburn, Augusta, Bangor, Biddeford, Gardiner, Lewiston, Portland, Saco, Sanford, South Portland, Waterville and Westbrook.