Former Maine Senate President Troy Jackson is facing renewed scrutiny over angry confrontations with colleagues as he moves closer to becoming the Democratic Party nominee challenging Republican Sen. Susan Collins in November.

Jackson emerged as the presumptive nominee after his supporters captured more than 460 of the 500 delegate positions filled ahead of a special state convention Saturday in Bangor. 

The gathering will include 601 delegates tasked with formally selecting a replacement for Graham Platner, who withdrew after a sexual assault allegation that he denied.

According to the Bangor Daily News, interviews with more than two dozen current and former lawmakers and political operatives described repeated outbursts during Jackson's six years as Maine Senate president, including shouting matches and a 2021 confrontation in which he threw a plastic water bottle during a dispute over prescription drug legislation.

Campaign adviser BJ McCollister acknowledged "moments when he let his frustration get the better of him" but said Jackson accepted responsibility.

"Troy regrets the moments when disagreements became too heated," McCollister said. "But passion for the issues he advocates for should not be confused with physical intimidation or bullying."

Another adviser described "heated, often two-way disputes" over legislation.

"Troy Jackson is passionate and deeply invested in the people and policies he advocates for," the adviser said.

One participant in meetings with Jackson said they felt "nervous" because his outbursts could escalate quickly.

"It was very aggressive," the person said. "It's one thing to be screaming when you're just mad about the world or sad about the world. But his screaming felt like intentional intimidation. So you would feel like then, what else is he going to do?"

Supporters contend Jackson's intensity reflects his commitment to working-class Mainers.

Former state Rep. Charlotte Warren, who criticized Jackson publicly after a 2021 argument but now supports his campaign, said, "There needs to be more passion when you are making the decisions we are making up there."

"There was nothing physical. But we were very forcefully trying to win our way. It is what you do in politics. It wasn't my finest hour. It wasn't Troy's finest hour," Warren said.

Former Maine House leader Maureen Terry also defended Jackson while acknowledging difficult interactions.

"When he has an issue that's important to him, he'll do whatever it takes to get things to a better place," Terry said. "I had about 100 meetings [with Jackson], some were really benign and some were a little more volatile, for sure. We got some good work done. We also had some misses, for sure."

Jackson has highlighted his work on universal free school meals and Maine's paid family and medical leave program.

Asked whether other revelations could sink his campaign, Jackson said voters "know I wear my heart on my sleeve" and that he is "passionate about the issues," adding that there "isn't going to be anything" that will derail him.

Jackson has said advocates sometimes need "to make the people in charge so uncomfortable that they can't ignore you anymore."

"And that's something I actually have become pretty good at," he added.

Collins, first elected in 1996, is seeking a sixth term and chairs the Senate Appropriations Committee.

Democrats need a net gain of four seats to regain Senate control, making Maine one of the party's most important targets.