The Minnesota Senate on Wednesday unexpectedly shot down a massive, $1.5 billion public works and infrastructure package, splintering a long tradition of bipartisan support for distributing state money to projects intended to boost local economies.

Hundreds of Minnesota cities and townships would have benefited from spending in the proposal, which emphasized transportation improvements, public campus buildings and water treatment upgrades. Supporters promised it would have generated tens of thousands of jobs.

The bill failed by a single vote, setting off a fresh round of partisan jabs between leaders of the politically divided Legislature and raising fears that very little will be accomplished in a legislative session that has just over two weeks remaining.

“It’s really hard to understand when people are elected and they come here and vote against the best interests of their constituents,” said Senate Majority Leader Tom Bakk, DFL-Cook. He vowed that Republicans who voted against the bill would pay a political cost in an election year in which all 201 legislative seats are on the ballot.

“I think they’ll have to answer for that on the campaign trail,” Bakk said.

Every member of the Senate’s DFL majority voted for the bill, along with a single Republican, Sen. Carla Nelson of Rochester. But, because so-called “bonding bills” utilize the state’s borrowing capacity to pay for their project lists, they require a three-fifths vote to pass.

Republicans said the measure was too expensive. The $1.5 billion price tag is considerably higher than past bonding bills, and a half a billion dollars more than what DFL Gov. Mark Dayton asked for in his own bonding request. The governor’s plan included an additional $300 million in spending from other sources.

“There’s a lot of room to negotiate, a lot of room to compromise. We just need to get serious on the part of the DFL,” said Senate Minority Leader David Hann, R-Eden Prairie. He said Republican senators were not lobbied for votes by the bill’s DFL backers, and pointed out that a number of Republicans did vote for a trimmed-down, $1 billion project list that the DFL majority rejected.

Bonding packages are a long-standing election-year custom at the Capitol. With the state as partner, local governments and public institutions get help paying for community-geared projects that would otherwise be financially out of reach.

For every project that gets funded, the state has billions more in requests waiting to make the final list.

The local projects funded by bonding bills also give lawmakers headed for re-election fights good concrete accomplishments to adorn their campaign literature.

The last election year the Legislature failed to produce a bonding bill was 2004. Bakk suggested Wednesday that could happen again this year, noting that Republicans who control the House have not yet produced a project list.

“We may end up going home this session without a bonding bill,” Bakk said.

Dayton, who had praised the Senate DFL proposal, has been an enthusiastic supporter of bonding bills, which he frequently touts for their job-creating potential.

His spokesman released a brief statement from the governor after the bill fell in the Senate.

“The Republicans killed the bonding bill,” Dayton said.

To date, House Republicans have only said they intend to propose $600 million in bonding projects. GOP House Speaker Kurt Daudt has been elusive about when he’ll publicize a list.

“We are working on a bill,” said Daudt, R-Crown. By law, the Legislature must adjourn for the year no later than May 23.

Daudt has prioritized the two chief Republican goals this year, to use the state’s projected $900 million budget surplus for a mix of tax reductions and spending on roads and bridges. He said the bonding bill should be more narrowly focused on transportation and infrastructure projects, and called the Senate’s $1.5 billion total “super excessive.”

“Before the next two weeks are up, we’re going to work on tax relief and we’re going to work on funding roads and bridges,” Daudt said.

But so far, there have been few visible signs that House and Senate leaders are working to settle wide differences over what to do with the surplus.

The looming election season hangs over the Capitol, and on Wednesday Daudt and Bakk separately predicted that the other party would take the blame if the session ends without major accomplishments.