A legislative effort to expand the MBTA’s board of directors with additional municipal representation seemed to get lost in the shuffle during the Sunday-Monday marathon legislative session.

Both branches approved a budget rider in their fiscal year 2023 spending bills that would add two more seats to the T’s oversight and management board, but the push to bump the panel up from seven members to nine is now suspended in lawmaking uncertainty.

Gov. Charlie Baker sent back the original board expansion proposal (H.5116) with amendments seeking to change how the two new members would be selected and what qualifications they would need. The House adopted Baker’s changes; the Senate didn’t take it up during the last formal session on Sunday and Monday.

Lawmakers could revive the measure during informal sessions that will continue into January, though any single lawmaker’s objection could stall progress, so the idea will need to have unanimous support.

The Legislature originally sought to add one seat that would have been appointed by the mayor of Boston and another filled by a municipal official representing one of the 51 cities and towns in the T’s service area.

Baker returned that measure with a different approach. Instead of giving Boston’s mayor outright power to select an MBTA Board member, he proposed requiring the mayor to submit a shortlist of three city of Boston employees with “experience in transportation operations” to the governor, who would get the final say.

His proposal also axed the idea for another municipal official and called for the second board member to be someone with “experience in human resources management and talent acquisition,” a change Baker said would “ensure the board has that valuable expertise as the MBTA continues to work on its staffing needs.”