Both the Southwest and Bottineau light-rail lines are imperiled by a nearly $1 billion transportation proposal being considered by Minnesota lawmakers.

A number of provisions adopted by the Republican-led Transportation Conference Committee late Monday would prohibit counties, cities, regional railroad authorities and the Metropolitan Council from spending money on new light-rail projects. Any proposed LRT project would have to gain legislative approval first.

“I haven’t thrown up yet, but I do have a very strong stomach,” said Hennepin County Commissioner and transit advocate Peter McLaughlin. “This would destroy our capacity to build out the transit system, and is destructive to the economic health of Minnesota.”

The proposal is not yet final, and is still subject to negotiation, said Rep. Paul Torkelson, R-Hanska, who co-chairs the conference committee. “We are open and available to work on it and we could amend this further if necessary. We hope the governor’s office engages us in thoughtful and significant negotiations.”

The proposed language bars the Met Council from issuing certificates of participation (COPs), an obscure financial instrument to raise $103.5 million toward construction of the $1.9 billion Southwest line.

Without this final piece of local funding, it is unlikely that Southwest would qualify for a $929 million federal grant covering half the project cost.

“It is hard to understand whether the Republicans’ obsession with killing the Southwest light rail project has blinded them to the horrific implications of their overly broad policy proposals, or whether their desire to advance the agenda of a few isolationists has led them to abandon their commitment to support local control when it comes to transit planning,” Met Council Chair Adam Duininck, said Tuesday in a prepared statement.

The regional planning body envisions extending the reach of the existing Blue and Green lines to the northern and southwestern suburbs by 2021, bolstered by several bus-rapid transit lines.

The Southwest light rail line, which would link downtown Minneapolis to Eden Prairie, has been controversial due to its route and funding issues, and has provoked a federal lawsuit to block it.

The Transportation Committee proposal would also gut the Counties Transit Improvement Board (CTIB), which raises money for metro-area transit projects through a quarter-cent sales tax and a $20 fee on new car sales. CTIB was expected to pay about a third of both the Southwest and Bottineau lines, as well as contribute to four big bus projects — the Gold, Riverview, Rush and Orange lines.

Torkelson noted that CTIB has already discussed dissolving itself. That move that would have freed the board’s five member counties to raise the transit tax to a half cent. But those talks failed last month when the board could not agree on an exit payment for Dakota County.

Under the law, counties in Minnesota can levy up to a half-cent sales tax for transportation purposes, and about two dozen have opted to do so. However, the Transportation Committee bill indicates the five CTIB counties — Hennepin, Ramsey, Dakota, Washington and Anoka — would first need voter approval before imposing such a tax.

The Met Council also claims the proposal would force a 10 percent cut to Metro Transit bus routes. This is less draconian than a previous version of the bill, which would have resulted in a 40-percent cut to bus service, the council said. The proposed cuts and a possible fare hike have prompted a series of protests and informational leafleting by transit groups and local chambers of commerce in recent weeks.

On Tuesday, a group of Minneapolis students who ride Metro Transit buses to school rallied against the cuts. Metro Transit said 10,282 student passes are used at 52 high schools with total ridership at 4.2 million in 2016.

The committee set aside $30 million to help mitigate the Met Council’s looming $74 million deficit, due largely to decreasing revenue from the state motor-vehicle sales tax, and increasing demand for Metro Mobility service. The council said Tuesday a $35 million deficit would remain, despite the cash infusion. The Met Council itself, now appointed by the governor, would be overhauled under the proposal to a 27-member board of local elected officials.

Star Tribune staff writer Tim Harlow contributed to this report.