A proposal to build a massive rival to the Panama Canal across the middle of Nicaragua was overwhelmingly backed by lawmakers Thursday, capping a lightning-fast approval process that has provoked deep skepticism among shipping experts and concern among environmentalists.

The National Assembly dominated by President Daniel Ortega’s leftist Sandinista Front voted to grant a 50-year concession to study, then possibly build and run, a canal linking Nicaragua’s Caribbean and Pacific coasts to a Chinese company whose only previous experience appears to be in telecommunications.

The legislation approved by a 61-25 vote contains no specific route for the canal and virtually no details of its financing or economic viability, simply granting the Hong Kong-based company exclusive rights to study the plan and build the canal if it proves feasible in exchange for Nicaragua receiving a minority share of any eventual profits.

Ortega’s backers say the Chinese will transform one of the region’s poorest countries by turning a centuries-old dream of a Nicaraguan trans-ocean canal into reality, bringing tens of thousands of jobs to the country and fueling an economic boom that would mimic the prosperity of nearby Panama and its U.S.-built canal.

“One of Nicaragua’s great riches is its geographic position, that’s why this idea has always been around,” Sandinista congressman Jacinto Suarez said during Thursday’s legislative debate. “Global trade demands that this canal is built because it’s necessary. The data shows that maritime transport is constantly growing and that makes this feasible. Opposing it is unpatriotic.”

The Hong Kong company will now begin a study of the project’s feasibility that will last many months, said chief project adviser Bill Wild, one of a number of Western experts hired by the firm to provide advice ranging from engineering and environmental planning to public relations.

He said it was too early to say if a widely reported project cost of $40 billion would turn out to be accurate. While rising demand for shipping appears to make a compelling economic case for the new canal, it is impossible to predict before the study is complete if the project will turn out to be financially feasible, he said.

The canal project will require financing from international investors.

“There’s a compelling commercial reason to build the canal,” Wild said. “We have to prove now that the actual rate of return that the investors will get is adequate.”

While the company has said almost nothing about the canal’s route, it would certainly cross Lake Nicaragua, the country’s primary source of fresh water. If one of the world’s largest infrastructure projects ever is actually built, the water used by the canal’s locks could seriously deplete the lake, environmentalists say.

“Approving this is unconstitutional, fraudulent and damaging to the interests of Nicaragua,” Eduardo Montealegre, the leader of opposition legislators, said during the assembly debate Thursday.

Global engineering and shipping experts say those concerns are real and that lowered demand for massive container shipping and increasing competition from other potential routes may mean that the Nicaraguan canal will simply prove economically unfeasible.

Either way, the quick march of the canal project through the National Assembly has set off a backlash from environmental and other activists, who held a series of marches this week to protest the granting of rights to the HK Nicaragua Canal Development Investment Co., without any open bidding process or details of its financing.

“Nicaragua isn’t for sale. Nicaragua belongs to all Nicaraguans and isn’t the private property of Ortega and his family,” the Movement for Nicaragua, a coalition of civil-society groups, said in an open letter to the country Wednesday.