Candidates for Maine's 1st Congressional District, from left, Independent Marty Grohman, Republican Mark Holbrook, and U.S. Rep. Chellie Pingree, a Democrat, chat prior to a debate sponsored by Maine Public, Tuesday at Bowdoin College in Brunswick. Credit: Robert F. Bukaty | AP

The candidates seeking to represent to Maine’s 1st Congressional District divided on humans’ role in climate change but agreed on the need to get money out of politics during a polite and, at times, jovial debate Tuesday night.

U.S. Rep. Chellie Pingree, a Democrat, and independent state Rep. Marty Grohman agreed that human action has played a role in the earth’s shifting climate and that government regulation has a role in combating it. Pingree said that she supports a tax on carbon emissions, while Grohman said “I would support a carbon tax but I don’t believe that it will cut fairly across the economy.”

Republican Mark Holbrook, on the other hand, said that the body of scientific research supporting the idea that humans have affected the climate is actually “far from settled and fraught with a lot of bias.” The Brunswick resident said he opposes a carbon tax.

The candidates shared a stage Tuesday evening at Bowdoin College in the third and final debate of a race that will be among the first federal elections decided by ranked-choice voting.

The debate was moderated by Maine Public. It was live streamed online and will re-air on TV at 8 p.m. Thursday.

The campaign of Grohman, a Biddeford resident, appears pinned to the hope that the new voting system could lead to an upset in Democratic-leaning district and allow him to unseat Pingree, of North Haven, who has won her five past races in the district by convincing margins.

[Ranked-choice voting poses greater threat to Pingree than either of her opponents]

But in recent weeks and during the last debate, the independent has more visibly been at odds with Holbrook than with the frontrunning incumbent.

Last week, for instance, Grohman asked several state agencies to investigate whether Holbrook broke state law by calling himself a psychologist — an alleged misrepresentation that the Republican denies.

Grohman struck an amiable tone Tuesday and sought to diffuse campaign tensions with gifts for both of his opponents.

He gave Holbrook a Whitman’s Sampler in reference to the Republican’s earlier statement that he’d have as hard a time picking a favorite among President Trump’s policies as he would among chocolates. Holbrook handed the box off to Pingree.

Credit: Troy R. Bennett | BDN

The candidates were in agreement on seeing the the tide of money that’s surged into American politics in recent years as a problem, but none saw it as easily solved. Holbrook noted his “paltry” fundraising compared to his opponents.

Unlike Maine’s 2nd Congressional District — where out-of-state money has poured in to support both U.S. Rep. Bruce Poliquin, the incumbent Republican, and challenging Democratic Assistant Maine House Minority Leader Jared Golden — the state’s southern congressional race has seen relatively little national attention or cash flow.

[Pingree’s challengers take shots at each other in 1st District debate]

In this environment, Pingree has retained a commanding fundraising lead. As of the most recent campaign finance filings, she’d raised approximately $720,000, while Grohman raised $354,000 and Holbrook brought in $89,000.

The debate had few tense exchanges, but two came while the candidates were questioning each other.

Pingree asked Holbrook about whether the administration’s immigration policies were hurting Maine businesses that rely on seasonal immigrant workers. In response, the Republican suggested that getting more Mainers to work should be the priority and that it is addiction that’s causing the state’s workforce problems.

“If they weren’t strung out on opioids we’d have people who want to work,” he said.

Another more heated moment came as Holbrook questioned Grohman on abortion, repeatedly asking him to define the start of life — a question the independent sidestepped.

In their closing statements, Pingree told voters that she’d be a check on the president, while Groman pledged to be free from the sway of the political parties.

Holbrook stressed that he’d be accessible to voters and presented himself as an alternative to “career politicians.”

CORRECTION: This story previously misstated Grohman’s position on a carbon tax. He said he would support one but is worried about its potentially unequal economic impact.

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