This story is part of a series focusing on climate change in key Senate races on the ballot in November.

At a Glance:

• Sen. Susan Collins of Maine has the strongest pro-environment voting record among Senate Republicans, but lost big environmental groups’ support over her votes backing President Donald Trump.

• Maine Speaker of the House Sara Gideon, who helped shepherd a package of climate legislation into law last year, is well-funded, well-known in the state, and ahead in polls.

• Many environmentalists are working to flip the Senate to Democratic control rather than backing a Republican moderate who hasn’t been able to advance solutions or block drilling in the Arctic.

Eighteen years ago, Sen. Susan Collins (R-Maine) stood with eight other GOP senators to block President George W. Bush’s plan to open the Arctic National Wildlife Refuge to oil drilling. To let the oil companies in, Collins said, “would be akin to wasting resources that should rightfully be there for future generations.”

But in 2017, while voicing misgivings, she voted to open the pristine wilderness area to oil exploration as part of President Donald Trump’s big tax cut bill, which she supported.

That vote began the unraveling of the environmental community’s long-standing support for Collins. 

Now, large membership groups like the League of Conservation Voters and Sierra Club are lined up against Collins in what is turning out to be a difficult bid for a fifth term in office. She has been trailing in polls behind Democratic challenger Sara Gideon, who for four years has served as Speaker of the Maine House of Representatives.

Collins has the strongest pro-environment voting record in the Congressional GOP, and is one of the few party leaders who has consistently accepted the science on humanity’s role in climate change.

But the green groups, like a slew of progressive and women’s organizations that have abandoned Collins—labor unions, Planned Parenthood, the Human Rights Campaign, Emily’s List— say her support for Trump and his agenda have made it impossible for them to support her.

“We needed Senators, especially Republican Senators, to stand up to the Trump administration, the most anti-environmental administration ever,” said Tiernan Sittenfeld, senior vice president of government affairs for the League of Conservation Voters. “Unfortunately, on far too many occasions, when we really needed Senator Collins’ support, she wasn’t there.”

Collins Faced No-Win Decisions Under Trump

Collins’ decision-making in the Trump era—often airing doubts but ultimately throwing her support behind the president—has become the stuff of Saturday Night Live satire. After prolonged reflection, she supported Supreme Court Justice Brett Kavanaugh’s confirmation and Trump’s impeachment acquittal.

Those high-profile votes spurred Democrats around the country to contribute money for Collins’ defeat. As a result, Gideon has raised $23 million, outpacing Collins’ $16 million haul, and making it the most expensive U.S. Senate race in Maine history.

James Melcher, a political science professor at University of Maine-Farmington, said that Collins’ political future would have been equally shaky if she had broken from the GOP on the key votes.

“Donald Trump has repeatedly put her in situations where she cannot win,” said Melcher. As it was, Collins’ vote for Kavanaugh helped tamp down an almost-certain GOP primary challenge from the right, possibly by then-Gov. Paul LePage, who had twice proven he could win statewide office in Maine.

Collins can fairly argue that her environmental voting record hasn’t changed much under Trump—her score on the League of Conservation Voters scorecard now hovers near her lifetime average of 61 percent substantially higher than that of any other current GOP Senate candidate. She voted against both Scott Pruitt and Andrew Wheeler when Trump nominated them to head the Environmental Protection Agency and opposed the rollback of the Obama administration’s Clean Power Plan. But she supported many other Trump nominees opposed by environmentalists, including Kavanaugh, who has a record of skepticism about federal authority to regulate greenhouse gases.

In fact, Collins’ environmental voting record has see-sawed. She previously won the LCV’s endorsement both in 2008, when she was one of just three Senators with a perfect 100 percent on the league’s scorecard, and in 2014, when she scored zero, casting votes in support of the Keystone XL oil pipeline and against clean energy tax credits.

Collins’ supporters argue her record reflects that she is not beholden to party or ideology. “Despite which party controls the White House, Senator Collins has always taken a pragmatic, thoughtful approach to our climate – and has always sought to find common ground and forge compromise rather than focus on what might divide us,” said her campaign spokesman, Kevin Kelley, in an email.

Early in the Obama administration, Collins and Sen. Maria Cantwell (D-Wash.) co-sponsored “cap-and-dividend” legislation as an alternative to the “cap-and-trade” bill then foundering in the Senate. It would have put a price on carbon, but less directly than a tax, while distributing the revenue in “dividend” checks to citizens to help offset increased energy costs.

But no big climate program ever made it through the Senate in the Obama years. And with Majority Leader Mitch McConnell (R-Ky.) firmly opposed to economy-wide climate legislation, Collins has not pushed further. She did not sign on to a “cap-and-dividend” measure now before Congress that is similar to her own 2010 bill.

In the current Congress, Collins has been a co-sponsor of bills prohibiting withdrawal from the Paris climate accord, calling on Congress and the president to act on climate, and supporting regional greenhouse gas reduction programs. All were dead on arrival in McConnell’s Senate. 

She is one of seven Republicans in the bipartisan Senate Climate Solutions Caucus, but the group lacks the cohesiveness or clout of the GOP environmentalist bloc that Collins joined in 2002 to block Arctic drilling. Before her vote for Trump’s 2017 tax bill, Collins was the lone Senate Republican to join a failed effort to strip Arctic drilling from the package.

“I honestly don’t think she’s changed that much” from her voting record in the past, said Melcher. “It’s just that the Trump presidency has made it a lot harder for her brand of bipartisanship to work well.”

Gideon Brings Money and Name-Recognition to the Fight

Gideon has something that no previous Democratic challenger to Collins has been able to bring to the race: a serious chance of winning. She is far better funded than the Democrats in the last two lopsided contests, each of which Collins won by more than 30 points. 

As Maine House Speaker, Gideon is well known in the state and has the kind of moderate profile that has appeal in a state where one-third of the electorate is independent.

Last year, Gideon helped shepherd a big package of climate and clean energy bills into law in Maine with bipartisan support. If elected, Gideon said she would push legislation to achieve net-zero greenhouse gas emissions by 2050, and fight to undo Trump’s regulatory rollbacks. “Investing in renewable energy and moving towards a carbon neutral future will help combat some of the threats to Maine’s key industries like warming waters, ocean acidification and drought,” Gideon said, in announcing her climate plan.

Collins has attacked Gideon for being a co-sponsor of a carbon fee-and-dividend bill that never made it through the Maine Legislature last year. “Maine workers can’t afford Sara Gideon,” said one of Collins’ ads, asserting that the bill Gideon supported would have raised the cost of fuel by 40 cents per gallon. In fact, the carbon fee that Gideon backed would have started at just 4 cents per gallon, and revenue would have been returned to Maine citizens in dividend checks. The cap-and-dividend plan that Collins herself co-sponsored in Congress a decade ago took much the same approach.

In any case, Gideon’s current climate plan doesn’t include carbon fees.

Gideon defeated two progressive supporters of the Green New Deal in the Maine Democratic primary, and she neither endorses nor criticizes that idea. In an interview with Bustle, she said the Green New Deal is about “facing the challenges that we have today in a forward-looking way.”

There’s an additional element of uncertainty in the Maine Senate race because of the “ranked choice voting” process the state adopted in 2016. Voters may select as many candidates as they like in ranked order. If no candidate gets more than 50 percent on the first ballot, the second choices of some voters—those who selected the least popular candidate for their first choice—will come into play, with potentially unpredictable results. 

The two independent candidates in the race both are running on energy and climate issues: Max Linn, a financial planner from Bar Harbor, whose signature issue is opposition to a planned hydropower transmission line from Canada; and self-described “teacher, organizer and grandmother” Lisa Savage, a progressive who embraces the Green New Deal.  

The Takeaway:

Collins has a relatively strong climate record, if viewed in isolation. But Senators don’t operate in isolation. With Trump in the White House and McConnell at the Senate Majority Leader podium, Collins has not been in a position to make much difference on climate, even if she accepts the science. Gideon’s work turning climate legislation into law in Maine means she knows the issues as well as the political pitfalls. That’s just icing on the cake for many environmentalists, who are inclined to support any Democratic challenger to Collins to help tip the Senate into Democratic control and wrest it from McConnell’s hands.