Massachusetts Gov. Charlie Baker urged lawmakers today to adopt his plan to overhaul management of the MBTA. The plan sets up a potential clash with the unions.

Hundreds of union members filled the largest hearing room at the State House. They listened while Baker defended his plan to shake up the MBTA.

“Let me make one thing clear here: I want to fix the T," Baker said. "I do not want to privatize the T, I do not want to slash services, I do not want to lay off hundreds of T employees.”

But a union representing some T employees held a rally before the hearing opposing the bill. And the head of the union testified it would roll back labor protections and open the door to Big Dig era abuses.

Baker’s bill would create a management board to step in and take control of the MBTA. The board would have the power to review and reopen labor contracts. Also, it would weaken binding arbitration and temporarily suspend the so-called Pacheco law, which limits the T's ability to hire outside, nonunion contractors.