The future leadership of the nation’s largest transit system, including the nomination of the first woman to hold the top job, was unexpectedly cast into doubt by state lawmakers on Wednesday.
Leaders of the Democratic-controlled State Senate indicated that they would not vote on a proposal by Governor Andrew M. Cuomo that would position Sarah Feinberg, a close ally of Mr. Cuomo’s, to become the Metropolitan Transportation Authority’s next chairwoman.
The move was the latest rebuke of Mr. Cuomo by members of his own party as the governor tries to navigate several crises and overlapping investigations that have left him politically weakened.
The governor had nominated Ms. Feinberg, 42, on Tuesday to succeed Patrick J. Foye, the chairman and chief executive officer of the authority, which runs New York City’s subway and buses and two commuter train lines.
Mr. Cuomo’s plan was to have Ms. Feinberg share what were Mr. Foye’s duties with Janno Lieber, who would oversee the transit system day-to-day operations as the authority’s chief executive.
But splitting the job that way required legislative approval that would have given Mr. Cuomo even greater control of an agency over which he already holds tight reins.
As currently structured, the combined roles require Senate confirmation, but under Mr. Cuomo’s proposal, he and future governors would have sole authority to appoint the chief executive. The authority’s chair would still have needed Senate confirmation.
Critics of the governor’s move, including Richard Ravitch, a former authority chairman, saw it as an attempt to institutionalize his power over the M.T.A.
The two roles have been held by different people in the past, but a 2008 commission led by Mr. Ravitch helped spur legislation that reunited the roles into a single job as part of an effort to restore the chief executive’s independence.
The proposal was introduced in the Legislature this week, the last week of this year’s legislative session. But when Senate Democrats met to discuss it on Tuesday, it quickly became clear there was not enough support for the bill, said Michael Gianaris, a Democrat and the Senate’s deputy majority leader.
“The governor is attempting a restructuring of the top echelon of the M.T.A. with very little notice and in such a way that the members of the Senate aren’t comfortable,” Mr. Gianaris said. “The notion that we were going to rubber stamp an effort to have even less oversight and more consolidation of power in the executive is not something we’re interested in.”
Mr. Gianaris said that lawmakers had raised concerns about the structure of the bill and its timing and even about Ms. Feinberg herself. Mr. Gianaris said that she “had frequently taken to the podium to echo the governor’s attacks and that kind of politicization is not something we’re interested in.”
He added, “The idea of dropping something like that at the 11th hour expecting us to rubber stamp it is a huge miscalculation.”
Neither the M.T.A. or Mr. Cuomo’s office responded immediately to requests for comment.
It was unclear whether the Assembly, where Democrats also hold the majority, would move to vote on the bill.