TWO OF THE STATE’S leading environmental groups are split on which candidate is the best to represent the Plymouth and Norfolk Senate district, which includes six coastal communities dealing with climate change and a town that is home to a controversial natural gas compressor station.

The Environmental League of Massachusetts endorsed the Republican incumbent, Patrick O’Connor of Weymouth, while the Sierra Club is supporting his Democratic challenger, Meg Wheeler of Cohasset.

The two candidates are not Trump-Biden polar opposites on the environment. Indeed, their campaign websites trumpet very similar themes – a 100 percent renewable energy future, opposition to the Weymouth compressor station, and promotion of assorted green initiatives. One key difference is that O’Connor touts bills related to the environment that he has filed as a state senator as well as his membership on the Senate Committee on Global Warming and Climate Change.

“The big difference is that we’ve been able to work on this and create a record of results,” said O’Connor.

Not so fast, says Wheeler, who argues that O’Connor has filed amendments and come out in support of environmental causes but has accomplished very little. She says O’Connor has not been a leader on climate change and was not successful in blocking the compressor station, which was built to speed natural gas through pipelines serving New England and Canada and has come under fire from a large group of politicians concerned about perpetuating the use of fossil fuels and increasing emissions in environmental justice communities.

“We are feeling the effects of climate change now,” Wheeler said. “It makes you wonder. Is this the best we can do?”

Wheeler is a first-time candidate who runs her own consulting business after years in the accounting field, first at Grant Thornton and then at the company that manages the Harvard University endowment. She is counting on a big turnout for Democrats to help her defeat an incumbent who has a big advantage in name recognition and fundraising.

The fact that he is one of just four Republicans in the Senate has mobilized some of his supporters. A super PAC affiliated with Republican Gov. Charlie Baker, for example, has spent $53,594 on behalf of O’Connor’s campaign over the last two months, which is more than what Wheeler has raised for her entire campaign this year.

Wheeler says being a Democrat could be an advantage during this election and afterwards, since Democrats control the Legislature. She says many voters in the district realize a Democrat could accomplish more on Beacon Hill than a Republican.

“I don’t think being a Democrat is enough, but I do think there is value in having a seat in the Democratic caucus,” she said. “If being a Democrat helps me get more done, so much the better.”

O’Connor, who won a special election in 2016 to replace his former boss, Robert Hedlund, the current mayor of Weymouth, fashions himself a Charlie Baker Republican, someone who can work with members of both parties to get things done. Citing the popularity of Baker, he says that’s what voters want.

“People are sick and tired of party over people,” he said. “We need to collaborate, come together, and find common ground.”

Like Wheeler, O’Connor expects a big turnout for the election and says the onus is on him to make the case that he’s done a good job. “I’ve been presenting bipartisan solutions,” he said. “I think people are satisfied with that.”

The Environmental League of Massachusetts endorsed 50 state candidates this year, and two of them were Republicans – O’Connor and Rep. Brad Jones of North Reading, the House minority leader. Clare Kelly, executive director of the League’s Action Fund, said she believes climate change and the environment are bipartisan issues and the organization wants to support Republicans who feel that way.

“His record of supporting our issues is something we appreciate and want to continue to support,” Kelly said of O’Connor.  “And diversity is – it’s not a key factor – but it’s something we consider,” she said of backing Republicans with good environmental records.

The Sierra Club, by contrast, endorsed 51 candidates for the Legislature and all of them were Democrats. The decisions about whom to endorse at the Sierra Club are made at the community level by members. Michael Mullaley led that effort in the Plymouth and Norfolk district, which O’Connor took as a bad sign because the Hingham resident has financially supported the senator’s opponents in previous elections.

Mullaley acknowledged O’Connor and Wheeler  are similar on many environmental issues, but he said the key factor for him is effectiveness. He said pollution is a huge issue in the district, which encompasses Cohasset, Duxbury, Hingham, Hull, Marshfield, Norwell, Scituate, and Weymouth.

“In the district there’s a lot of frustration. It’s not just the compressor station. Half the people you  know have some sort of cancer,” he said. “He says the right things. But the question is, has anything actually been done?”