Puerto Rico Gov. Ricardo Rossello said Sunday evening that he will not resign in the face of public furor over an obscenity-laced leaked online chat, but he will not seek re-election or continue as head of his pro-statehood political party.

Protesters said they were not satisfied by Rossello's concessions, and pledged to continue demonstrations that have filled the streets of Old San Juan for more than a week.

"He's stretching things out. We had hoped he'd taken the decision to resign. He's making the people's pain last longer," said Emmarie Morales, a protester from the southeast coastal town of Patillas. She said the governor's decision would not end the protests. "He's given us more strength to protest. We aren't going to sit around watching Netflix."

In a brief video posted on Facebook, Rossello also said he looked forward to defending himself against the process of impeachment, whose initial stages are being explored by Puerto Rico's legislature.

"In spite of everything, I recognize that apologizing isn't enough, that only my work will help restore confidence ...," the governor said. "Facing that scenario, I announce to you that I will not seek re-election next year."

The 889 pages of chat on the encrypted app Telegram between the governor and 11 close allies and members of his administration, all men, showed the governor and his close advisers insulting women and mocking constituents, including the victims of Hurricane Maria.

Demonstrators in kayaks gather in front of the governor's residence in San Juan on Sunday. (Dennis M. Rivera Pichardo/Associated Press)

Since the chat leaked July 13, hundreds of thousands of outraged Puerto Ricans have marched to Rossello's official residence in the largest protest movement on the island since Puerto Ricans successfully demonstrated to demand an end to U.S. Navy military training on the island of Vieques more than 15 years ago.

Puerto Rico's justice secretary, Wanda Vazquez, would assume the governor's role under the territorial constitution's line of succession if Rossello should quit.

The upheaval comes as the U.S. territory is struggling to recover from Hurricane Maria and trying to restructure part of $70 billion US in debt amid a 13-year recession. Puerto Rico is home to more than 3 million U.S. citizens who do not have full representation in Congress or a vote for president.

"Today, I have the great responsibility to direct my efforts, and those of my administration, to keep searching for ways and means for us, united before God, to be able to keep guiding our island," the governor said.

Pressure to resign

On Monday morning, tens of thousands of Puerto Ricans were expected to take over one of the island's main highways to demand Rossello's resignation as legislators considered whether to take the first steps of the impeachment process.

Arriving late Sunday to prepare for Monday's march was Nicole Quintana, a 32-year-old dentist, along with her husband and their three-month-old son.

"We had to do it for him," she said, gesturing to her son. She said they drove about two hours from the coastal town of Isabela to participate. "Finally people have said: 'Enough is enough. This ends here."'

Pressure on Rossello to step down has grown throughout the week as the chorus calling for his resignation grew to include Puerto Rico music superstars Ricky Martin, Bad Bunny and Residente and a string of U.S. politicians including Congress members from both parties, several Democratic presidential candidates and Puerto Rico's non-voting representative in Congress.

People from the Dallas-Fort Worth Puerto Rican community gather to protest Rossello outside the Adobo Puerto Rican Cafe in Irving, Texas, on Sunday. (Tom Fox/The Dallas Morning News via AP)

Rossello was elected governor in November 2016 with nearly 50 per cent of the vote, and he had already announced his intention to seek a second term. A graduate of MIT with a doctorate in genetics, he is the son of former Puerto Rico Gov. Pedro Rossello, who flew to the island to marshal support after the chat was made public.

The governor belongs to the New Progressive Party, which seeks statehood for the island, and he is also a Democrat. Most of his time has been spent seeking federal funds since Hurricane Maria devastated the island on Sept. 20, 2017, and battling austerity measures implemented by a federal control board that Congress set up to oversee the island government's finances.

The upheaval against Rossello prompted at least four cruise ships to cancel visits to Puerto Rico, and many officials worry about the impact a resignation would have on the already fragile economy as the island rebuilds from Maria, a Category 4 storm that caused more than an estimated $100 billion US in damage.

Another concern is the recent string of arrests involving federal corruption charges targeting Puerto Rico officials, among them two former agency heads, including former education secretary Julia Keleher.