When Maine seemed poised to pass the nation’s first temporary ban on new data center development, the country started to pay attention.

National media outlets homed in on the story, highlighting Maine’s pending legislation as a potential indication of state governments’ appetite for the centers, which have emerged as a major political flashpoint — with a dozen other states considering similar legislation.

Then came the veto.

Gov. Janet Mills shot down the measure, LD 307, late last week. The Democrat said that she would have enacted the bill if it had included an exemption for a development proposed at the former Androscoggin Mill in Jay.

Critics — including environmental advocates and other political figures — were quick to condemn the move. Some prominent members of her own party said they would have made a different call.

But others, including labor unions and developers eyeing Maine, praised Mills for taking a stand for local interests amid national scrutiny.

The move could have major political ramifications for Mills, who is a little more than 40 days from perhaps the biggest test of her public life: The Democratic U.S. Senate primary on June 9. Polls show her badly trailing political newcomer Graham Platner in the race for the chance to unseat Republican incumbent Susan Collins.

GUBERNATORIAL DEBATE

The Democrats vying to replace Mills in November mostly said they would have signed the moratorium bill.

Speaking at a weekend debate hosted by the Midcoast Villager, four of the five candidates said they would have signed LD 307. Clean energy entrepreneur Angus King III was the only candidate who did not say he would have signed the measure, though he avoided explicitly stating that he would have vetoed it.

“If I was the governor, it wouldn’t have gotten to this point,” King said.

The others — Secretary of State Shenna Bellows, former Maine Senate President Troy Jackson, former Maine House Speaker Hannah Pingree and former Maine Center for Disease Control and Prevention Director Dr. Nirav Shah — all said they would have enacted the bill.

Bellows said there are potential uses for the artificial intelligence technology powered by large data centers, but she argued that protecting Maine’s natural resources and electricity rates is crucial.

“Data centers are a boondoggle perpetrated by crypto billionaires who are gobbling up everything in sight,” Bellows said. “And the costs to society, especially given clean water and the importance of electricity, are huge.”

Jackson, a frequent Mills critic, said the bill was well thought out, adding that Mills should have attempted to compromise with the Legislature sooner. He criticized Mills for running what he calls a “very top-down” administration.

“She’s concerned more about big business than she is about workers,” Jackson said.

Pingree called Mills’ veto “unfortunate,” reiterating concerns about data centers’ potentially negative impacts on the environment and utility rates. If elected, Pingree said she would advance a moratorium on her first day as governor.

Shah condemned Mills’ move as “an error.” He said Maine needs time to study centers’ impacts and to nail down the best regulations.

“If we are going to have data centers in Maine — and a big if, I want to be clear — then my general approach is let’s do it right, not do it fast,” Shah said.

He also pushed back on claims that data centers create long-term jobs, and he expressed concerns about transparency, noting that several development proposals only came to light after lawmakers started considering a restriction.

SENATE RACE

A spokesperson for Collins, whom Mills is currently running to unseat in the Senate, chimed in Monday to say the senator believes data center development should be left up to local communities.

“While Senator Collins typically does not take a position on state legislation, she recognizes that data centers can benefit certain communities like Jay that generate their own electricity, by providing critical revenue and jobs,” spokesperson Blake Kernen said in a written statement.

Meanwhile, Graham Platner, the front-runner in the Democratic primary for Collins’ seat, told NBC News ahead of Mills’ veto that she should sign the bill, which he called a “Band-Aid.”

Platner said the federal government should create AI standards centered around labor protections.

“My biggest problem with data centers and AI is that it’s very clear that AI is coming,” Platner told NBC. “And in every moment in human history where a new, transformative technology arises that increases productivity, when it’s left in the hands of corporate power, it is always used to disenfranchise people. It is always used to, frankly, impact workers negatively.”

When asked for Platner’s response to Mills’ veto, a Platner spokesperson referred back to that interview.

BIZ WEIGHS IN

The Maine State Chamber of Commerce said it “appreciates” Mills’ veto, saying in a statement issued last week that projects like the Jay proposal “can represent meaningful opportunity” for communities in need.

The second district of the International Brotherhood of Electrical Workers, which represents union members across New England, also commended Mills’ veto, calling the proposed moratorium overly broad in a statement this week.

“Maine can protect ratepayers, communities and natural resources without shutting the door on responsible projects that can create good jobs and help redevelop industrial sites,” Vice President Michael Monahan said in a written statement. “Projects like Jay and Sanford deserve to be judged on the facts.”

While Mills’ veto was rooted in protecting the Jay project, it also appears to clear the way for another proposal in Sanford.

Randy Gibbs, the latter project’s lead developer, said the governor is being unfairly criticized for the veto, which he called “courageous.”

“Such a moratorium may be a feather in the cap of national data center opponents, but it is unnecessarily harmful to Maine communities and workers,” Gibbs said in a written statement.

Lawmakers will take up the veto on Wednesday, but the bill appears unlikely to generate the necessary two-thirds majority to overturn Mills’ rejection.

Staff Writer Randy Billings contributed to this story.

Editor’s note: This story was updated April 28 to correct the spelling of Blake Kernen’s name.