The Middle Tennessee Mayors Caucus — the coalition of regional mayors advocating for mass-transit funding — have sent a letter to members of the General Assembly in support of Gov. Bill Haslam’s contentious transportation funding bill, which is slated to make its debut on the House floor Wednesday.

The full Senate could also take up the proposal today, though the House vote will undoubtably be the proposal’s most challenging, particularly since even the majority leadership has flip-flopped their…