Maine House Speaker Sara Gideon, a Democrat, is expected to formally announce in the coming weeks that she's running for Republican Sen. Susan Collins' seat in 2020, five Democratic sources confirmed to HuffPost.

She will likely launch her campaign shortly after the close of the state's legislative session on June 19, the three Democratic sources in Maine and two national Democratic strategists said.

Defeating Collins, the Maine moderate who infuriated liberals with her vote to confirm Brett Kavanaugh to the Supreme Court, is key to Democratic hopes of winning back control of the Senate in 2020. Gideon is a top-tier recruit for the race and is expected to have at least the tacit backing of establishment groups like the Democratic Senatorial Campaign Committee and EMILY's List.

At the same time, the Senate GOP is marshaling its resources to defend Collins, who has long outperformed other Republicans on the ballot in Maine.Gideon hinted last October that she would toss her hat in the ring following Collins' controversial vote for Kavanaugh.

"Maine deserves a champion in the US Senate," Gideon wrote in a Facebook post at the time. "After November I will be seriously considering how I can elevate the voices of people who deserve and demand to be heard and represented in Washington, DC."

Gideon did not immediately respond to HuffPost's request for comment.Sweet appears to be Gideon's most direct competition for the Democratic nomination. She finished a surprising third in that gubernatorial primary in 2018 and has already won the endorsement of the progressive group Democracy for America this time around. She also relied on public financing for that race, which won't be available in the Senate contest.

"In the U.S. Senate, [Sweet will] be an unabashed champion for abortion rights, Medicare for All, a $15 minimum wage, organized labor, and criminal justice reform," Yvette Simpson, the president of Democracy for America, said in a statement on Thursday. "In 2014, far too many National Democrats made a huge mistake by giving Susan Collins a pass on what should have been a reelection fight. In 2020, we can't just fix that mistake by ending Susan Collins' career, we must replace her with someone who'll be a strong fighter for our shared progressive values."

Nationally, establishment-backed Democrats have rarely lost Senate primaries in recent years. The Maine primary is June 9, 2020.Collins won reelection with 61% of the vote in the Democratic wave year of 2008 and 68% of the vote in the Republican wave year of 2014. Democrats hope to give her a stiffer test next year.

A Critical Insights poll last month shows her approval rating in Maine has dipped 10 percentage points since her Kavanaugh vote in October and now sits at 41%, with 42% disapproval.

In the weeks following Kavanaugh's confirmation, two separate crowdfunding initiatives raised millions of dollars for a potential Democratic challenger to Collins, which should provide whoever wins the primary with a significant financial boost. One of the funds has already pulled in $3.8 million, while the senator's 2014 challenger spent only $2.4 million over the course of the entire race.

Heading into Kavanaugh's confirmation, Collins was generally considered one of three swing votes. She ultimately supported him despite the multiple sexual misconduct allegations raised against him from the 1980s, drawing outrage from Democrats and abortion rights activists.

Collins, one of two Republican senators to publicly support abortion rights, has nonetheless voted for more than 30 of President Donald Trump's judicial nominees who signaled they were against abortion, including Kavanaugh.

Hayley Miller and Kevin Roubillard, HuffPost, June 14, 2019

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June 15, 2019

Voices4America Post Script. Is this the woman who knocks hypocritical Susan Collins off her throne? Happy to meet her #BlueSenate202