Minnesota Republicans want President Trump's transportation secretary to deny Minnesota almost $900 million in requested funding for the Minneapolis-to-Eden Prairie Southwest Corridor light rail project.

It would upend a project that has been working through stages of approval for almost a decade.

Opponents of what would be the biggest-ever public works project in Minnesota have done everything they could to stop it. They fought Southwest light rail before city government, blocked clearance at the state Capitol and went to court.

But this might be the biggest threat yet.

A letter to Transportation Secretary Elaine Chao represents a show of force by Republican state lawmakers trying to convince a Republican administration to pull critical financial support for Southwest.

House Transportation Policy Committee Chair Linda Runbeck, R-Circle Pines, said while the prior Democratic presidential administration had a welcoming take toward rail transit projects and fostered the Southwest light rail plan, the jury is still out on this one.

"We're recognizing there's a new sheriff in town," she said.

Runbeck is among the 84 legislators who have signed the letter to Chao that calls Southwest a "grossly wasteful project." Signers include House Speaker Kurt Daudt, top GOP lawmakers on transportation and Republicans from around greater Minnesota.

Even though cities up and down the proposed 14-mile line have signed off, Runbeck and her colleagues say there are too many legal and financial uncertainties as well as ridership questions to go forward.

Runbeck said she's not worried about Minnesota losing out while another region snaps up the federal money.

"I look at the fact that 40 percent of what the federal government spends is borrowed," she said. "We have to start to recognize that we can't just look to the federal government to fund any want and wish that we have."

The Metropolitan Council, which oversees the Southwest project, has yet to send a response to the federal agency.

The planned route for the Southwest light rail line, as of January 2017. Courtesy of Metropolitan Council

Nearly $160 million has already gone into the project. Since 2008, the Metropolitan Council says there have been more than 870 public hearings, open houses, community workshops and other meetings regarding the project.

DFL Gov. Mark Dayton called the Republican letter "unhelpful."

Dayton and the project's backers say Southwest would alleviate traffic by giving commuters another option, and he said reversing course now would be a mistake.

"It's just going to create nightmarish traffic jams. It's going to constrict the economic vitality of this entire region which affects the entire state," Dayton said. "So, it's very short-sighted. It's very crude political calculation at the expense of the best interests of Minnesota, especially five, 10, 20 years down the road."

A standoff over the project held up a state transportation funding package and other construction borrowing last year when leaders couldn't agree on how to proceed.

This year, Republicans are also making plans in case the line goes through. Their just-released transportation funding bills would make clear that the state won't cover light rail operating costs in the future.

That would shift to the counties where the routes operate and possibly result in higher fares to ride.

The line is supported by the Twin West Chamber of Commerce and other businesses that see it as a way to reduce congestion and get workers from the suburbs to the city and vice versa.

But opponents say a fixed-route line isn't the way to go.

Republican Rep. Jenifer Loon, whose Eden Prairie district includes the line, left her name off the letter. She says other issues are her priority.

"My position on Southwest has not changed. I'm opposed to the line. I have concerns about it, which I've shared with my community. I really don't have anything else to say about it," Loon said.