PORTLAND, Maine — After a nasty campaign against a fellow legislator with a historically big campaign bankroll, state Rep. Ben Chipman cruised to victory in the Democratic primary for Maine Senate District 27 in the state’s largest city on Tuesday.

He becomes the favorite to win Maine’s most Democratic district in November after easily winning a primary that saw Portland’s party establishment fracture between Chipman, who only joined the party last year, and Rep. Diane Russell, a fourth-term lawmaker and progressive favorite who unofficially registered a shocking third-place finish.

The race was marked by a fundraising haul for Russell that was among the highest ever in a Maine primary, dueling ethics complaints against both legislators and last-minute tricks aiming to subvert Chipman’s campaign.

“I think a lot of the negative attacks backfired against me in the last few days,” Chipman said. “Voters were frustrated with it.”

Chipman won 53 percent of votes to Russell’s 23 percent in the Portland race, with Dr. Charles Radis in second place at 24 percent. He’ll run against Republican Mark Lockman and the Green Independent Party’s Seth Baker in November.

In the five other Democratic primaries for the Maine Senate:

— Rep. Justin Chenette beat Rep. Barry Hobbins for the nomination to the seat to be vacated by Sen. Linda Valentino in District 31, which stretches from Saco to Hollis and part of Buxton. It’s a stunning win for the 25-year-old Chenette over Hobbins, an Augusta institution in his 26th year of legislative service, and he will be favored over Republican William Gombar of Old Orchard Beach.

— Rep. Mark Dion won with 44 percent of votes to Portland City Councilor Jill Duson’s 39 percent and former Rep. Ann Peoples of Westbrook with 17 percent in the race for the open seat in District 28, in western Portland and part of Westbrook. Dion is the favorite to beat Republican Karen Usher of Westbrook in the second-most Democratic district in Maine.

— Former U.S. Senate nominee Shenna Bellows of Manchester declared victory over Gardiner City Councilor Terry Berry in Senate District 14 in southern Kennebec County, with 82 percent of votes. Sen. Earle McCormick, R-West Gardiner, is leaving the seat, which hasn’t been won by a Democrat since 2004. However, the district leans slightly Democratic and looks like a swing seat this year. On the Republican side, retired Navy Adm. Bryan Cutchen of West Gardiner was leading Gardiner City Councilor Maureen Blanchard with six of 11 precincts in.

— Sen. Susan Deschambault of Biddeford easily beat former Mayor Joanne Twomey in Senate District 32 in York County from Kennebunkport to Lyman. She’ll face Republican Steve Martin of Biddeford. She beat him by 16 points in a March special election.

— A rematch in the 2014 race between Sen. Brian Langley, R-Ellsworth, and Democrat Ted Koffman of Bar Harbor is up in the air. Surry nurse Moira O’Neill was leading him by about 180 votes with 24 of 31 precincts reporting.

The race between Chipman and Russell overshadowed the others on Tuesday. On policy, the two aren’t much different. They backed Democratic presidential insurgent Bernie Sanders and are as progressive as the city they represent.

But the campaign illuminated divides. Chipman allies slammed Russell in Bangor Daily News blogs. Mailers from Russell’s campaign hit Chipman for joining the party in September 2015 and featured a photo of him reviewing a campaign mailer from his seat in the House of Representatives. Senate Minority Leader Justin Alfond, D-Portland, endorsed Chipman on Monday, decrying Russell’s “gutter politics.”

In the campaign’s last days, Democrats in Portland also got letters at their doors attacking Chipman that said they were paid for by a group funded by Americans Take Action, a national progressive network. Stickers showed up on Chipman signs with a URL to a website posting a tenant complaint against him.

Russell’s massive fundraising edge also became campaign fodder. As of late May, she raised $89,000 behind well over 1,000 contributions, mostly from small donors across the country amassed through a huge email list that Russell has nurtured as a champion for buzzy quests, including marijuana legalization and abolishing Democratic Party “superdelegates.”

It left Chipman, who ran under Maine’s taxpayer-funded election system, with less than $13,000 to run his campaign as of last month. Radis raised less than $14,000 privately.

Campaign finance was a major issue in the race, with ethics complaints filed against both candidates. They were addressed by the Maine Ethics Commission on Tuesday in Augusta as Chipman and Russell wrangled for votes.

No final action was taken on Tuesday, but the panel voted that sufficient grounds exist to investigate whether Russell violated Maine election law with her use of the email list.

It also reopened a probe into a May complaint against Chipman from a Russell supporter who questioned if he violated a loophole in Maine election law that allows campaign volunteers to contribute unreported money for “invitations, food and beverages.”

Russell’s lawyer said the list was the candidate’s personal property and denied wrongdoing. Chipman said his arrangement was legal and modeled after other campaigns, saying it was a maneuver from Russell’s camp to distract from her own ethics issues, including past fines to her political action committee.

At the East End Community School on Tuesday, A. Jan Berlin, who lives on the Eastern Promenade, said he was open-minded at the beginning of the campaign, but he supported Chipman because he was “really disappointed in the PAC revelation stuff.”

“That was a game-changer,” he said.

Michael Shepherd joined the Bangor Daily News in 2015 after three years as a reporter at the Kennebec Journal. A Hallowell native who now lives in Augusta, he graduated from the University of Maine in...