The transportation fund currently supports roughly $800 million per year in state borrowing, which in turns leverages about $750 million in matching federal grants. But DOT officials say as aging, overcrowded highways and bridges demand more costly repairs, $1.5 billion-to-$1.6 billion won’t get the job done, and something closer to $2 billion per year will be needed. Based on that assumption, the transportation fund hits insolvency around 2025 or 2026. Fonfara, who says bonding is a key tool for economic development and to help poor communities in lean fiscal times, introduced a bill last year that would have wrested control of the State Bond Commission from the Executive Branch and given it to the legislature. It sailed through the finance committee, but legislative leaders then tabled it and instead tried to negotiate a middle ground with Lamont.