(Corrects to show that Garcia Padilla will give televised address, not press conference)

SAN JUAN, Nov 30 (Reuters) - Puerto Rico could face a public transportation shutdown starting Monday, as talks go to the wire on approving a controversial crude oil tax hike proposed to shore up the island's finances.

In what would be a major escalation of Puerto Rico's debt crisis, the local government is planning to shut down its bus and city train service after Governor Alejandro Garcia Padilla was unable to convince enough members of his party to agree to raise the tax by 68 percent. The increase was to be used to back a $2.9 billion bond sale.

Garcia Padilla was scheduled to give a televised address later Sunday evening.

"I depend on the bus for everything," said Mercedes Ortiz, 84, waiting at a bus stop in downtown San Juan to travel to a pharmacy to buy prescription medicine. "I'm against raising the oil tax because it will be a big blow to a lot of people, but I hope the governor does not stop the buses."

The shutdown would impact an estimated 75,000 people who use the government's Metropolitan Bus Authority, the privately run MetroBus, the Tren Urbano commuter train service as well as a bus rapid transport (BRT) that brings commuters from west of San Juan, Transportation Secretary Miguel Torres Diaz said in written comments provided to Reuters Sunday.

It would impact 2,800 workers who work for the Highway & Transportation Authority as well as private companies contracted to service the private bus line, commuter train and BRT system. It would impact road repairs across the island and halt improvement work about to begin on major highways in San Juan and on the islands west and east coast, he added.

It could also jeopardize future funding, the U.S. Department of Transport warned last week.

Highways and Transportation Authority Executive Director Javier Ramos Hernandez said Sunday that the HTA would "activate the forces within our reach to safegard the installations of the public corporation, its regional offices and other dependencies." The HTA has activated a coordination plan with the Police Department to protect HTA property.

TALKS CONTINUING

After the legislature failed to approve the tax measure during its regular session, the governor convened a special session last week, but lawmakers called a recess until Monday.

Senate Finance Committee Chairman Jose Nadal Power told Reuters that negotiations between the House leadership and Garcia Padilla's office were continuing Sunday.

"The governor's office is working with leaders to come up with a solution tomorrow. Aside from the main topic, the oil tax, we must come up with a solution even it if is temporary," Nadal Power said. "We are facing an emergency situation in terms of public transportation and a solution must be found."

House Speaker Jaime Perello and administration officials have been discussing different versions of amended legislation through Sunday. House lawmakers want more certainty regarding a planned tax reform expected to be introduced early next year. Senators are also pushing for guarantees that the HTA will make the operational changes required to become self-sufficient.

"We are all hoping for a consensual solution, but if the House is not able to come up with sufficient support for this measure, we must look for a Plan B," Power said. "If the shutdown happens tomorrow, we will have to find a solution tomorrow to stop it from extending."

While the transit links are centered in the San Juan metropolitan area and only serve a small proportion of Puerto Rico's 3.6 million population, the closure would be the first shutdown of a major public service as a direct result of the government's fiscal crisis.

The crude oil tax hike was to back a bond sale of up to $2.9 billion, which would repay a $2.2 billion loan to the island's government development bank (GDB) from the HTA, as well as support mass transit operations. That issue has been pushed back from November into early 2015.

CONTINGENCY PLANNING

As lawmakers and administration officials were negotiating over the tax, contingency plans were being arranged to get the island's population to work or school in the morning.

Mayors of San Juan, Bayamon, Carolina and Catano were establishing plans for municipal buses and trolleys to provide service for some major routes. Private public cars will also be allowed to pick up passengers on established bus routes.

Union and management employees planned a protest outside the capital on Monday morning.

"This is a service that has been provided for years, and many students, maids, working people and the poor depend on it," said Jose Velez, a 69-year-old security guard. "It's going to affect them very badly.

(Reporting by Reuters in Puerto Rico; Editing by Megan Davies, Bernard Orr)