Minneapolis park commissioners voted unanimously Wednesday to ask voters this fall to authorize raising $300 million over 20 years to repair and replace aging neighborhood park facilities and improve maintenance cycles.

“This is something that is going to be critical to the city of Minneapolis, and each of our neighborhoods,” Commissioner John Erwin said.

The mechanics of how the proposal will reach the November ballot are undecided, since the board can’t put it before voters on its own. The Minneapolis Park and Recreation Board’s preference is to have the City Council put the matter before voters, according to its president, Liz Wielinski. But if the council balks, it has three other options: the Legislature, the Charter Commission or a direct petition.

Also unresolved is whether the park referendum, and another on whether to extend an existing extra levy for schools, will work together or if those goals will be pursued separately. There has been talk of coordinating the two campaigns, but no concrete steps to date, supporters of both said this week.

The school board last week voted to put its levy, which otherwise expires in 2017, before voters in November. The school board doesn’t plan to define how much it will ask for and for what purposes it would spend the money on until this spring, after polling.

The proposal initially would raise about $15 million per year for parks. Much of it would be spent to replace or upgrade 50-year-old buildings; some spending would address critical repairs to keep buildings viable until long-term needs are met. Mowing and tree-trimming are examples of maintenance activities that would be accelerated. Superintendent Jayne Miller said the renovations might adapt buildings and playfields to recreational changes, such as changing a baseball diamond to soccer.

The Park Board pulled the trigger on seeking the higher tax after almost three decades of complaining by commissioners about insufficient funding. The Park Board vote was 8-0, with Commissioner Brad Bourn absent.

But the proposal is a tough sell for City Council President Barbara Johnson. “It could be a real hit to the taxpayers, and I’m concerned about it,” Johnson said. She said she hasn’t decided how she’ll vote. Wielinski asked park supporters to contact their council members to ask them to vote for the plan.

The most immediate precedent for having two spending referendums on the city ballot was 2000, when voters gave 72 percent support to extending the school levy and 67 percent backing to a $140 million bond issue for libraries.

The Park Board had been moving to add a third spending referendum to that year’s ballot, but then-Mayor Sharon Sayles Belton, concerned that a park proposal might hurt the other two spending proposals, struck a deal to budget more park money. That fell apart under her successor, R.T. Rybak, in a budget squeeze triggered by soaring pension costs and a state aid cut.

The board has three other options for putting the proposal on this year’s budget. It could ask the Legislature to mandate a referendum; the board will huddle with local legislators next week. The Charter Commission could vote to authorize the referendum, with the council determining only ballot wording. Or park supporters could trigger a referendum if they collected roughly 6,900 signatures.

Supporters of the proposal said they’ll try to raise $400,000 to sell it to voters. Mark Andrew, chairman of the Save Our Minneapolis Parks campaign committee, said $60,000 has been raised. That doesn’t count a separate $50,000 paid for polling by the Jay & Rose Phillips Family Foundation.