Sen. Susan Collins speaks to reporters after presenting at Fruit Street School on Jan. 10.

AUGUSTA, Maine — A national survey released Thursday found U.S. Sen. Susan Collins of Maine had the highest disapproval rating of any senator in 2019’s last quarter as she enters a campaign for a fifth term in which she is one of national Democrats’ top targets.

The Republican once polled as Maine’s most popular politician and won her 2014 race with more than two-thirds of votes, but her 2018 vote for U.S. Supreme Court Justice Brett Kavanaugh kicked off a massive Democratic campaign against her and the news comes amid impeachment proceedings against President Donald Trump that will be high-stakes for Collins.

The senator’s re-election bid has already seen the most fundraising of any Maine race ever and unprecedented amounts of early ad spending. Roughly $10 million in TV ads were booked in 2019 alone, according to Advertising Analytics, which projected there would be $55 million spent on ads over the course of the race.

Collins’ approval rating has sunk sharply since Trump took office in the first quarter of 2017, when the Maine senator registered a 67 percent approval rating, according to Morning Consult. In the final quarter of 2019, the firm said her rating stood at 42 percent.

Her disapproval rating of 52 percent in Maine during that period was highest among senators. Collins overtook Senate Majority Leader Mitch McConnell, R-Kentucky, the only senator who had a higher rating than her in 2019’s third quarter.

Maine Gov. Janet Mills, a Democrat, had 47 percent approval and 45 percent disapproval during the same period. That was largely flat from 2019’s third quarter, but Mills still had the seventh-highest disapproval rating among governors near the end of her first year in office.

Collins has become a top target for Democrats in a national environment in which it will be an uphill battle to reclaim the Senate from Republicans. Her seat in liberal-leaning Maine is one of only a few Republican-held seats in Democratic-leaning states up in the 2020 cycle.

The electoral threat to Collins is still uncertain. Democrats face a primary in June featuring House Speaker Sara Gideon of Freeport, Hallowell lobbyist Betsy Sweet, former Google executive Ross LaJeunesse of Biddeford and Saco lawyer Bre Kidman. Educator Lisa Savage of Solon is running as a Green and at least three others are aiming to run as independents.

Gideon — the nationally backed likely frontrunner in the primary — outraised Collins during the summer, though the incumbent had raised double what the House speaker had by that point. There also has not been a public poll in the race since June, when Collins led Gideon by 16 percentage points in a survey by Florida-based Gravis Marketing.

Michael Shepherd

Michael Shepherd joined the Bangor Daily News in 2015 after three years as a reporter at the Kennebec Journal. A Hallowell native who now lives in Augusta, he graduated from the University of Maine in...