ST. PAUL — Political calculations have complicated efforts in the Legislature to pass a public works financing package, a marquee bill being closely watched from water-starved Worthington to the campgrounds-in-waiting at the new Lake Vermilion State Park.

Neither the House nor the Senate has voted on a slate of projects as Democratic leaders maneuver to go beyond an $850 million handshake agreement with Republicans, whose votes are coveted because of borrowing bills, need three-fifths majorities to pass. Top Republicans say they won’t budge, even as the possibility of steeper tax cuts and other trade-offs are floated in exchange.

“I’ll never say never, but at this point my caucus is not interested in going above the agreed-upon amount,” said House Minority Leader Kurt Daudt, R-Crown. He was referring to a GOP pledge to help pass $1 billion in construction projects over two years. Last year, a $150 million plan was approved.

The bonding bill is considered a linchpin to the session’s completion. Until its size is nailed down, negotiators working on tax and spending plans can’t complete their work because the amount of annual debt payments must be accounted for and will determine the amount of surplus available for those other measures.

“Once we get the bonding bill figured out, we’re within striking distance” of adjournment, said House Speaker Paul Thissen, DFL-Minneapolis.

In the House, leaders don’t plan to bring a bill up until they’re sure they’ve locked down the 81 votes needed for passage, which would take at least eight Republicans if all Democrats hang together. The Senate hasn’t even rolled out a proposal yet, and it would take at least two Republican votes to reach the 41 required to pass a bill in that chamber.

With low interest rates and extra room before the state hits its debt cap, Democrats from Gov. Mark Dayton on down say now is an ideal time to authorize an ambitious list of construction projects. Those in the mix range from re-roofing college campus buildings to mid-size city civic center expansions to rehabilitation of public housing. But the competition is fierce, with giant projects like an ongoing Capitol renovation chewing up a large chunk of available funds.

“I’ll just name three projects: the Capitol at $126 million, the state security hospital in St. Peter at $56 million, the state prison in St. Cloud at $34 million. I’ve just given you three projects and that’s $200 million,” said House Capital Investment Committee Chairwoman Alice Hausman, DFL-St. Paul. “That’s how fast the $850 million goes.”

It’s possible that a separate bill funding projects with cash — needing only a simple majority — will advance as well.

Republican senators have given Democrats their position in writing. The GOP insists that the package be held beneath $850 million, with roughly one-third devoted to higher education projects. They don’t want to pay cash for the last installment of the state Capitol renovation, say sewer and water upgrades like southwestern Minnesota’s Lewis and Clark project are essential and won’t accept any transportation spending on light-rail projects. They also want at least $290 million in projects approved for districts represented by Republican members.

“Everything that needs to be done can get done within that limit,” said Sen. David Hann, R-Eden Prairie. “We see no reason to go higher.”

Senate Majority Leader Tom Bakk, DFL-Cook, said he hasn’t decided if they’ll move ahead with an $850 million bill or take his chances with a bigger one, knowing that some GOP members will find it tough to resist projects deemed critical back home.

“Smaller ones are always harder to pass because there is less in them,” Bakk said.