The partisan fight over Twin Cities mass transit that did much lawmaking damage at the Legislature last year has roared back in recent days, more menacing than before. This time, federal, state and local funding for Metro Transit — both for new construction and operations — is “under attack,” Ramsey County Commissioner Jim McDonough said. He pleaded for help from a Minneapolis Regional Chamber of Commerce audience last week. “This is a perfect storm.”

McDonough’s storm warning is spot-on. It demands action from Metro Transit’s backers — particularly in the GOP-allied business community. They know that a fully developed transit system in the Twin Cities is vital to the economic health of not only the metro region, but the entire state.

What they may not realize is that more than the controversial $1.9 billion Southwest light-rail line is being threatened. Republican-backed proposals at the Legislature and in Washington would undermine existing Metro Transit operations and block all of the region’s future rapid transit expansions, both bus and rail. This region’s ability to compete for talent with other urban areas and cope with a looming labor shortage would suffer if those proposals prevail.

Here are just some of the looming threats:

• President Trump’s proposed budget for fiscal 2018 would deny federal funds to Southwest light rail and all other future rapid-transit projects, all of whose budgets rely on receiving 50 percent of construction funding from the federal government.

• Republican legislators in Minnesota piled on by sending a letter to U.S. Secretary of Transportation Elaine Chao asking that she refuse to grant the expected $887 million federal outlay for Southwest — a project that has been 10 years in the making, has already spent $159 million, and is due to start construction later this year.

• GOP legislators propose to refuse to fund the state’s customary 50 percent of operating cost for any new rapid-transit line the Legislature does not explicitly approve.

• Republican budget proposals at the Legislature do nothing to narrow a growing deficit in Metro Transit’s operations. In fact, the House budget would enlarge the deficit in the next two fiscal years to $122 million, according to Metropolitan Council chair Adam Duininck. It also would require the share of operating costs met by fares to climb from about 22 percent to 40 percent. That would mean “effectively pricing most riders off the bus,” Duininck said.

Meanwhile, the proposed dissolution of the five-county Counties Transit Improvement Board, which would free willing metro counties to raise the sales tax to pay for transportation needs, is foundering. Dakota County — which plans to leave the board at the end of next year — is demanding a $29 million payout to agree to an early exit. That demand has produced an impasse that puts a darker cloud over future rapid-transit expansion.

Republicans defend their Metro Transit pinch as necessary to improved funding for Greater Minnesota roads. But as the Star Tribune reported last week, those counties already receive 68 percent of the state’s total transportation spending while paying less than half of transportation-dedicated state taxes. A similar pattern exists in state funding of education and aid to cities. The health of the Twin Cities economy makes that possible — and that health will suffer if Metro Transit investments lag.

Further, GOP critics of rail transit say it’s too costly and inflexible. But government per-passenger operating subsidies were lower for Metro Transit’s two rail lines in 2015 than for Metro Transit buses — and those buses required lower subsidies than all but one of the “opt-out” suburban bus lines. As the business community can attest, rail transit’s fixed location makes it a magnet for economic development. That’s not something Republicans typically scorn.

The Legislature’s rural-dominated Republican majorities seem hellbent on delivering highway funding to their own districts at the expense of transit in the DFL-dominated metro area. Minnesotans saw last year how damaging that tactic can be. GOP opposition to Southwest light rail took down a $1.3 billion transportation/bonding bill in the final minutes of the 2016 session.

Republicans made that “lose-lose” ploy work to their advantage in the last election. They’re trying for “win-lose” for their districts this year. Their own political friends should advise them that they are pursuing a flawed strategy. Making a loser of the metro area is not in the best interest of any Minnesotan.