San Juan Mayor Carmen Yulín Cruz talks to Sen. Bernie Sanders (I-Vt.) during a visit Oct. 27 to the Playita community in San Juan, Puerto Rico. (AFP/Getty Images)

Hurricane Maria destroyed Puerto Rico’s decades-old electrical grid when it made landfall on Sept. 20, rendering millions of island inhabitants without power.

On Tuesday, Sen. Bernie Sanders (I-Vt.) will unveil an ambitious $146 billion Puerto Rico recovery plan he says will allow renewable power sources such as solar and wind to provide about 70 percent of the island’s energy needs within the decade.

The bill, which has the backing of San Juan Mayor Carmen Yulín Cruz, also calls on Congress to consider retiring Puerto Rico’s debt and would give the island billions in additional federal funding for transportation, health care and education in the hopes of stemming a feared mass exodus to the mainland. It would also allocate funds to the Virgin Islands, which were similarly devastated by Hurricane Maria.

“This is the closest we have to a Marshall Plan for Puerto Rico,” said Ramón Luis Nieves, a former member of the Senate of Puerto Rico who has testified to Congress about the hurricane’s impacts.

Sanders's bill is highly unlikely to get a vote in Congress and is more generous even than the $94 billion requested by Ricardo Rosselló, Puerto Rico’s governor.

Sanders’s bill would give $62 billion to help the cash-strapped Puerto Rican government; $51 billion for economic development; $27 billion for infrastructure, including new energy infrastructure; and billions more for education and environmental remediation.

The Trump administration has requested $29 billion in emergency natural disaster funding to be shared between Puerto Rico, Florida, and Texas — but only a fraction is designated for Puerto Rico. That package is expected to pass.

“More than two months after Hurricane Maria, in the wealthiest nation in the history of the world, most of the homes in Puerto Rico and the U.S. Virgin Islands are still without electricity. This is beyond belief,” Sanders said. “Congress must work with the people of Puerto Rico to fundamentally transform its expensive, antiquated and unreliable system.”

Puerto Rico's energy grid is maintained by the Puerto Rico Electric Power Authority (PREPA), which has come under fire for what critics have called its slow and ineffectual response to the hurricane. PREPA drew congressional scrutiny for awarding a no-bid $300 million contract to Whitefish, a small Montana firm. PREPA, which filed, in effect, for bankruptcy last July, is the sole provider of electricity for the island's 3.4 million residents.

Conservative lawmakers and several members of Puerto Rico’s fiscal oversight board have called for parts of PREPA to be privatized.

“The board certainly considers privatization one of the options going forward,” Natalie Jaresko, the executive director of Puerto Rico’s financial oversight board, said to Rep. Louie Gohmert (R-Tex.) at a recent House hearing. “There’s currently a question that remains open to see whether it’s privatization of the entire power sector … or some select part.”

Sanders's bill, which would put $13 billion into rebuilding the electrical grids in Puerto Rico and the Virgin Islands, would bring the debate about privatizing PREPA to a head. The measure explicitly prohibits public infrastructure receiving federal aid, such as the electrical grid, from being transferred to private ownership.

But Puerto Rican officials say they are already working with private-sector companies to install solar panels and microgrids in remote sections of the island.

Sanders' bill would set aside $428 million in grants for homeowners and cities for solar panels and microturbines and more than $40 million for grants to improve home energy efficiency.

“The case for renewables is that it’s the cheapest way to do it, and certainly the cheapest in the island’s isolated communities,” said Steven Kyle, an economist at Cornell University who has reviewed Sanders’s bill. “Since they’re starting from zero, they have a unique opportunity here.”

Most engineers estimate that Puerto Rico could get up to 50 percent of its energy from renewable sources within the decade, according to Sergio Marxuach, public policy director at Center for a New Economy, a nonpartisan think tank on the island territory. “Seventy percent is definitely on the upper bound of what’s possible,” Marxuach said. “But, sure, if you throw enough money at a problem, you can do a lot of things.”

In a statement, Rosselló thanked Sanders for trying to help Puerto Rico, though he stopped short of offering an endorsement of the bill. “We are committed to rebuilding Puerto Rico smarter and stronger than ever before, but we need all the assistance we can get from the federal government,” Rosselló said. “We welcome all discussions and proposals being discussed in the United States Senate, including Senator Bernie Sanders’ proposed bill, that seek to provide the resources necessary to rebuild Puerto Rico.”

Luis Fortuño, the former governor of Puerto Rico, said that he thought it would be a mistake to prevent transferring parts of the electrical grid into private ownership. “You need a lower cost of power, and the only way to accomplish that is through a competitive process through the private sector,” said Fortuño, who added that he hadn’t read Sanders’ proposal and that he supports its greater public investment in renewable energies.

Experts have emphasized that the federal government should not simply replace Puerto Rico’s old grid with a new one similarly exposed to catastrophic storms.

A senior White House official told Reuters that the administration does not support rebuilding the original vulnerable grid. Sen. Lisa Murkowski (R-Alaska), who chairs the Senate Energy and Natural Resources Committee, has backed rebuilding Puerto Rico’s electrical systems with microgrids or through distributed energy — but the senator hasn't yet introduced legislation for doing so, according to a spokesperson.

“It’d be a phenomenal mistake to spend federal tax dollars rebuilding the polluting, expensive, decrepit grid,” said Judith Enck, who oversaw Puerto Rico as a regional administrator in the Environmental Protection Agency during President Obama's administration. “My great fear is FEMA will reconstruct the old grid — and when the next hurricane hits, it will all come tumbling down again.”

Nieves, the former Puerto Rican state senator, said that while he supports Sanders’s legislation, he fears an ideological debate over the energy grid’s future in Congress could lead to inaction. “The right says PREPA has to be privatized, and that’s the solution for everything; the left says it must remain a public corporation and is opposed to privatization,” he said. “In the middle of that debate lies the fate of the Puerto Rican people."

Sens. Elizabeth Warren (D-Mass.), Edward J. Markey (D-Mass.) Richard Blumenthal (D-Conn.), Kirsten Gillibrand (D-N.Y.) and Kamala D. Harris (D-Calif.) will co-sponsor Sanders’s bill, and a handful of other Democratic senators are considering doing so as well. It has also been endorsed by 73 liberal and labor organizations, including MoveOn.org, the Sierra Club, and the Service Employees International Union.

“I was glad to work closely with Senator Sanders on this far-reaching bill so that we can aid our fellow U.S. citizens and help them along a path to full recovery," Warren told The Washington Post.

Correction: This story incorrectly stated the number of Puerto Rico's residents. It has now been corrected.