Democrats are increasingly confident about their chances to flip Maine’s open Senate seat in 2020.

It would seem like an uphill climb to take on longtime incumbent Republican Susan Collins, who has held the seat since 1996 and has enjoyed high approval ratings in part by keeping Maine’s priorities as her focus in the Senate. She also has maintained her reputation as a New England moderate who can work across the aisle with Democrats.

But the 2020 ballot will be headed by President Trump, whose agenda and rhetoric have earned him high disapproval ratings in the state, which could ricochet down the ballot and hurt Collins.

A June poll funded by Gravis Marketing surveyed nearly 750 Maine “individuals,” (not necessarily voters) and found 41% “strongly disapprove” of the president while 35% “strongly approve” of his actions in office. Another 10% each fell into the “somewhat” approve and disapprove columns.

Collins’ own Senate actions have cost some support, say Democrats. She cast a key vote to confirm Supreme Court Justice Brett Kavanaugh, who liberals were eager to block from the bench. Her support of Kavanaugh has attracted significant opposition from liberal groups who are now eager to fund the effort to defeat her next year.

Collins now faces a bevy of Democratic hopefuls who want to become the nominee to challenge her in November as well as two GOP primary opponents and a possible list of independents who may add their names to the general election ballot.

And the four-term senator has not even decided yet whether she will be on the ballot a fifth time.

She told Bloomberg News she’ll win if she ultimately makes a bid for a fifth term.

“The people of Maine have known me, and they know that I have been a hardworking, independent advocate for them, who votes with integrity,” Collins told Bloomberg News. “Should I choose to seek reelection, I’m confident it will go well.”

Kevin Kelly, a spokesman for the Collins campaign, said she plans to announce after Labor Day whether she'll run for another term. He pointed out a group running ads against Collins has refused to disclose its donors. Collins, meanwhile, has been busy meeting with constituents.

"Sen. Collins has always traveled home to Maine nearly every weekend to meet with constituents, attend events, go to church, and even go to the grocery store where she is always talking to Mainers about a wide variety of concerns," Kelly told the Washington Examiner. "The people of Maine know and trust Sen. Collins. She will be reelected because she has worked hard to earn their respect. Mainers know she has always been a thoughtful, powerful, and independent advocate for them and for our state."

Last week, the Cook Political Report, a top, nonpartisan campaign ratings website, moved the Maine Senate race from “lean Republican” to “toss up,” in part because the nationally endorsed Democrat, Sara Gideon, managed to raise more than $1 million in the second quarter, even though she declared her candidacy about a week before the end of the fundraising cycle.

Gideon also enjoys some name recognition among voters as the speaker of the House in Maine’s state legislature, who has helped to pass liberal legislation, Cook Senior Editor Jennifer Duffy noted.

Duffy, who ranks Senate races, said Gideon appears to have “lots of room to grow” as a candidate and could pose a real threat to Collins, who has not experienced a close race for Senate since she was first elected by a five-point margin in 1996.

Collins easily won reelection in 2014 over Democratic opponent Shenna Bellows by 37 points.

But a Republican victory is not a certainty in Maine. Voters have alternated between Democratic and Republican governors and have twice elected independent Sen. Angus King, who votes with the Democrats.

“This could well end up being one of the closest Senate contests of the cycle and is in the Toss Up column,” Duffy announced last week.

While the Democratic Party is backing Gideon, she must win a June 2020 primary against several other candidates vying for a spot on the ballot, including ultra-liberal candidate Betsy Sweet. Sweet recently won a key endorsement from Justice Democrats, the group who helped facilitate Democrat Alexandria Ocasio-Cortez’s improbable primary victory in Queens, New York, in 2018.

Polling of likely Maine voters is scarce.

The Gravis-funded June poll matched Collins against Gideon and found Collins winning, 52% to 36%, and 12% undecided.

A July Morning Consult poll produced more worrisome results for Collins. It found Collins’ approval dropped a net 16 points from earlier in the year. Among those who disapprove of her job performance were 46% of independents, a key voting block in Maine.

Among Republicans, 61% approved of her job performance while 67% of Democrats said they disapproved.

The Senate’s Democratic campaign arm is working to link Collins as much as possible to the agenda of Trump and the Senate GOP lead by Majority Leader Mitch McConnell.

Collins voted in favor of the 2017 GOP tax cut plan, which Democrats have been successful characterizing as mostly a benefit for big corporations. And she has voted to approve a record number of conservative judges to the federal bench, which Democrats say will hurt women's reproductive rights.

Democrats need to win three to four Senate seats in order to retake the majority, depending on which party wins the White House and controls the tie-breaking vice presidential vote.

“After helping pass the GOP’s tax giveaway to giant corporations and the rich and voting to confirm dozens of President Trump's anti-choice judges, Sen. Collins is facing the toughest campaign of her political career because she's become an increasingly reliable vote for her Washington special interest donors and Mitch McConnell’s agenda,” Stewart Boss, spokesperson for the Democratic Senatorial Campaign Committee, told the Washington Examiner. “While Sen. Collins’ approval rating in Maine plummets to an all-time low, Democrats are in a strong position to flip this seat next year."

Republican strategists say Collins has advantages as an incumbent who remained focused on Maine and particularly the state’s business community and economy.

“I just think that Sen. Collins has a long track record of fighting for Maine-specific issues,” Republican political consultant Brent Littlefield told the Washington Examiner. “That, for many voters, transcends the national political atmosphere and I think that voters in Maine traditionally have looked to people who have fought for their state’s interest.”