SAN JUAN (Reuters) - Puerto Rico’s next governor remained up in the air on Thursday, just 24 hours before Governor Ricardo Rosselló was due to resign, as the U.S. territory’s Senate pushed a vote on his successor to Monday.

Rosselló, who is set to leave office at 5 p.m. ET (2100 GMT) on Friday, tapped lawyer Pedro Pierluisi to be secretary of state, pending confirmation by the legislature, and first in line to succeed him as governor.

But Puerto Rico Senate President Thomas Rivera Schatz said Pierluisi’s role as an attorney advising the widely-disliked financial oversight board directing Puerto Rico’s bankruptcy presented conflicts of interests and made him unacceptable.

“Pedro Pierluisi does not have the vote of the majority,” Schatz said in a fiery speech. “The lawyer for Puerto Rico’s number one enemy can’t be in charge of Puerto Rico.”

His chamber agreed to hear from Pierluisi on Monday, while the House is scheduled to vote on the nomination on Friday, making it more likely that Justice Secretary Wanda Vázquez, the second in line for governor, would take office.

Vázquez, who previously said she did not want the position, tweeted on Thursday that if the time comes, she would assume the governorship.

The speaker of Puerto Rico’s House of Representatives, Carlos Méndez, told reporters that Pierluisi could still become governor in the event his chamber fails to vote on or confirms the nomination during a Friday session. If the House votes against Pierluisi as expected, Vázquez would become governor, Méndez said.

Slideshow ( 9 images )

A 2005 Puerto Rico law suggests that the secretary of state could become governor without being confirmed by the House and Senate, according to José Julián Alvarez, constitutional law professor at the University of Puerto Rico Law School, who said he believed that law to be unconstitutional.

“The constitutional solution requires the secretary of state be confirmed by both houses of legislature before the governor resigns. If not the secretary of justice, under law, becomes governor,” he said.

Hundreds of thousands of Puerto Ricans took to the streets in recent weeks to demand Rosselló quit after the leaked messages unleashed rage over suspected administration corruption, slow recovery from 2017’s deadly hurricanes and the U.S. territory’s bankruptcy.

Street protesters have also accused Pierluisi of serving the interests of the federally-created oversight board, not the Puerto Rican public.

During Pierluisi’s second term as Puerto Rico’s nonvoting representative in Congress, he supported the 2016 passage of the PROMESA Act, which created a financial oversight board for the island’s government and a path to deal with its huge debt load.

In 2017, the oversight board filed a form a bankruptcy to restructure about $120 billion of the government’s debt and pension obligations.

At O’Neill & Borges, one of the law firms representing the board in the bankruptcy, Pierluisi has been an adviser on mediation and policy-related matters and provided “key assistance” on a deal to restructure Puerto Rico’s sales tax-backed debt, according to court filings.