Opponents of Question 1, the most expensive referendum in Maine’s history, spent more than three times as much money per vote as supporters, and they still ended up on the losing side.

That means those incessant TV, radio and online ads – not to mention countless mailers – did not produce the intended effect. It may have even turned some voters off.

“Once you reach a certain threshold, it’s not just diminishing returns, but it can start to move things in the other direction,” said Dan Shea, professor of government at Colby College in Waterville.

According to figures from the Maine Ethics Commission, the owners of Central Maine Power and their allies, including Hydro-Quebec, spent about $48 million (through registered ballot question committees) trying to persuade voters to reject Question 1, which called for halting construction of the New England Clean Energy Connect (NECEC) corridor through western Maine.

That works out to $289 for each of the 165,705 No votes cast.

By comparison, supporters of Question 1 – led by NextEra Energy, a competing power company, and some environmental groups – spent at least $21.8 million, or $90 for each of the 240,701 Yes votes, with 98 percent of precincts reporting.

Full spending reports from the ballot committees are not due until December, so those spending numbers are likely to increase because of last-minute buys.

Shea said it’s becoming increasingly common nationwide to see large amounts of money associated with ballot initiatives, citing recent hot-button referendums, or propositions, in California as examples.

“Whether big spending shapes the outcomes, the data is not at all clear on that,” he said.

Shea said if the two sides are lopsided but only one of them has enough resources to get their message out, that might make a difference. But with Question 1, he said, both sides had plenty of money, even if opponents outspent supporters. And he said the extra money spent by opponents may have had a negative impact.

Indeed, many voters expressed frustration over the barrage of spending and claims made in many advertisements and said that did impact their vote.

Shea said the same dynamic played out a few years ago, only it was even more lopsided. In 2017, supporters of an effort to bring a casino to York County spent more than $8 million to reach voters. The primary opposing ballot committee spent a little less than $700,000.

In the end, 83 percent of Maine voters rejected the initiative. For each vote in support, casino backers spent $146; for each no vote, opponents spent just $2.40.

Turnout in Tuesday’s election – more than 400,000 in Maine, or about 37 percent of the electorate – was the highest in an off-year election since 2009, when voters overturned a recently passed law that allowed same-sex marriage. But it was still far below turnout in presidential or gubernatorial election years.

Campaign spending has increased dramatically in recent years following the Supreme Court decision in Citizen’s United v. Federal Election Commission, which prohibits the government from restricting independent expenditures for political campaigns by corporations. That ruling also affirmed an earlier decision in Buckley v. Valeo that essentially found that spending money on political campaigns constitutes free speech.

Shea said those decisions make it difficult for any additional regulations to be placed on campaign spending.

“But if we can’t limit it, we can at least make it clear to voters where the money is coming from,” he said.

Last year, the U.S. Senate race in Maine between Republican incumbent Susan Collins and Democratic challenger Sara Gideon was by far the most expensive in the state’s history – topping more than $200 million. But the amount spent per vote in the Senate race was significantly less because of the much higher turnout on Election Day. Gideon’s campaign spent more than $142 per vote cast for the candidate, while Collin’s campaign spent more than $56 per vote collected.

Although CMP and its owners, Connecticut-based Avangrid Inc. and the Spanish firm Iberdrola, were willing to spend tens of millions to urge voters to reject Question 1, it’s still a relatively small percentage of what the NECEC corridor is expected to cost.

The cost of the 145-mile power line corridor through western Maine has been pegged at roughly $1 billion – $350 million of which already has been spent.

Even more money is going to be spent on legal costs. On Wednesday, Avangrid filed a lawsuit contesting the referendum question’s constitutionality, and the company said it plans to move ahead with the power line project.