Liberal upstart Graham Platner won Maine’s Democratic Senate primary on Tuesday night, defeating Maine Gov. Janet Mills weeks after the more establishment-backed pick ended her campaign.

The Associated Press called the race soon after polls in Maine closed at 8 p.m., where voters in the state are not only weighing in on one of the nation’s most significant Senate races but also on a comeback attempt for a controversial former governor and a contest to decide the next governor that features several famous names.

The primary elections mark the first chapter in what is expected to be a compelling year in Maine politics, one that represents Democrats’ best chance to oust Sen. Susan Collins ®, who is running for her sixth term, and will see a new governor elected.

Platner easily won Maine’s Democratic Senate primary.

But the question hanging over the race was whether a series of troubling revelations about his past will lead a significant portion of Democratic voters to back Mills, who ended her campaign in April after being unable to overcome Platner’s strong polling.

When the race was called Tuesday night, Mills was garnering around 20 percent support.

Platner has attempted to shake off the stories, which include allegations that he sent sexually explicit text messages to women while married and had volatile relationships with women. At an event on Friday, Platner declared that Mainers “have my back” — an allusion to the allegations — and said that would be clear on Tuesday when he wins the primary.

But multiple Maine Democrats have raised the prospect that the negative stories could lead to a sizable protest vote in the race. Mills even teased the idea.

“People have the impression that I ‘withdrew’ or ‘dropped out,’” Mills said. “But I simply suspended active campaigning. I am still on the ballot.”

Collins is running unopposed in the Republican primary.