House Speaker Sara Gideon, D- Freeport, a candidate for U.S. Senate, speaks at a "Supper with Sara" campaign event at the Poulin-Turner Union Hall in Skowhegan in this Feb. 19, 2020, file photo. Credit: Robert F. Bukaty | AP

AUGUSTA, Maine — A poll released on Thursday by Public Policy Polling shows Maine Sen. Susan Collins in a tight race to keep her U.S. Senate seat, while giving a slight edge to her leading Democratic rival, Maine House Speaker Sara Gideon, though the result is still within the margin of error.

Gideon had 47 percent support in a hypothetical general election match-up with Collins, while the incumbent Republican senator had 43 percent with 10 percent of voters undecided. The margin of error is about 3 percentage points.

The survey of 872 registered voters was conducted earlier this week by Public Policy Polling, a firm which generally conducts polling for Democrats. It is the second poll in the race for Maine’s U.S. Senate released in a span of a few weeks, following a Colby College survey released in mid-February that showed Gideon and Collins virtually tied in a general election match-up.

Both surveys show movement since earlier polling of the race, when Collins led Gideon by 16 points in a poll in June 2019. The Republican senator was one of the most popular in the country as recently as 2017, but has seen her approval ratings decline significantly since President Donald Trump took office.

The drop has been particularly dramatic among Democrats and independents, from whom Collins has drawn significant support throughout her career, as the Maine senator has fought to maintain her reputation as an independently minded senator in an increasingly polarized era of politics. She became a target for Democrats nationally after her vote to confirm Brett Kavanaugh to the Supreme Court in 2018.

Collins’ decision to acquit the president in the impeachment trial in early February was her latest vote where reactions were split along partisan lines. In the poll released Thursday, 75 percent of Democrats said they thought Collins voted to acquit Trump in order to protect him politically while only 13 percent of Republicans said the same.

Among independents, 51 percent said Collins voted to protect Trump, with 37 percent saying she thought Trump did not commit an impeachment offense and 11 percent undecided.

Collins is one of national Democrats’ top targets in 2020 and has already been the subject of significant outside spending with nine months still to go until the general election. The Republican senator has also raised a record amount of money for her re-election campaign, though she was outraised by Gideon during the last two quarters of 2019.

The poll released Thursday shows Gideon with slightly positive favorability ratings, with 34 percent of voters holding a positive opinion of her, compared with 32 percent negative and 33 percent undecided.

The House speaker will face progressive lobbyist Betsy Sweet, former Google executive Ross LaJeunesse and lawyer Bre Kidman in a June primary, with the winner set to face Collins in November. The Colby survey showed Gideon with a significant lead in the primary race.

Several independents are also looking to make the general election ballot, including former Green party hopeful Lisa Savage, who announced Wednesday that she had enough signatures to make the ballot. The election will use ranked-choice voting.

The poll released Thursday also asked Maine voters about presidential matchups, and showed two Democrats, former Vice President Joe Biden and Vermont Sen. Bernie Sanders, each with 10-point general election advantages over Trump with 6 percent of voters undecided, though both Biden and Sanders still had underwater approval ratings in the state.

Trump, whose approval rating sits at 42 percent in Maine, according to the poll, lost to Clinton by 3 points statewide in 2016, though he won by 10 points in the 2nd District. Barack Obama won Maine by 15 points in 2012.