Augusta, Maine - Maine Governor Janet Mills, a Democrat, has entered the race to challenge Republican Susan Collins for her US Senate seat.

"There are too many politicians in Washington, including Susan Collins, who have forgotten their principles and let bullies like Trump have their way, and it's hurting Maine people," Mills says in a campaign announcement video released on Tuesday.

"I've never backed down from a bully, and I never will," she adds.

The 77-year-old two-term governor touted her efforts to push back against the Trump administration, highlighting a lawsuit the state filed against the US Department of Agriculture's decision to defund school meals for children.

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The move came after Mills publicly sparred with Trump over an order banning transgender athletes from women's sports.

"If this President and this Congress were doing things that were even remotely acceptable, I wouldn't be running for the US Senate," Mills says in her video.

"I won't sit idly by while Maine people suffer and politicians like Susan Collins bend the knee as if this were normal."

If elected, Mills would become the oldest freshman senator ever at a time when many are clamoring for a generational shift in Congress. She was encouraged to throw her hat in the ring by 74-year-old Senate Minority Leader Chuck Schumer.

Also in the Democratic race for Collins' seat are oyster farmer and veteran Graham Platner, brewery owner Dan Kleban, and Jordan Wood, who was the chief of staff for former Representative Katie Porter.

Platner's campaign, in particular, has generated a lot of excitement in the race. He is endorsed by Vermont Senator Bernie Sanders, who previously spoke out against the prospect of Mills launching a bid for office.

"Graham Platner is a great working class candidate for Senate in Maine who will defeat Susan Collins," Sanders posted on X last Thursday. "It’s disappointing that some Democratic leaders are urging Governor Mills to run. We need to focus on winning that seat & not waste millions on an unnecessary & divisive primary."