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One of the most vulnerable incumbent Republican senators for 2020, Maine’s Susan Collins, is looking gradually weaker with each new bit of polling data from her state. She got a lot of bad publicity earlier this year when she replaced Mitch McConnell as the most unpopular senator in Morning Consult’s quarterly approval/disapproval ratings, likely in no small part the product of her crucial tie-breaking support for the confirmation of Brett Kavanaugh. Then she voted to acquit Donald Trump after his impeachment trial, which did not burnish her reputation for being independent of her party (her favorable/unfavorable rating deteriorated to 42/54 in a mid-February survey from Colby College). She did break with other Senate Republicans on an amendment that would have cut unemployment benefits in the coronavirus stimulus legislation.

But as the moment of truth approaches, Collins — who will face her toughest general election opponent ever in the likely candidate of Maine House Speaker Sara Gideon — continues to lose ground, according to a new Critical Insights poll reported by the Bangor Daily News:

The poll showed a further drop in approval for Republican Sen. Susan Collins since last fall, from 42 percent to 37 percent, while the share of voters who disapproved of her performance climbed to 52 percent, though her approval rating with Republican voters continued to rise. Independent Sen. Angus King remained popular, with 59 percent of voters approving of his performance.

Yeah, 37/52 is pretty bad, and unlike state officials she’s not in a great position to make herself look good on coronavirus response issues, remaining in the shadow of her party’s not terribly popular president. As my colleague Rebecca Traister noted in a profile of the Maine senator earlier earlier this year, Collins may have run out of luck and time:

Choosing between a party that now demands total fealty and a constituency she’s promised independence, Collins — a woman who has built her image around being a careful, thoughtful decision-maker — appears to have made no decision at all about the best way to keep her power. Instead, she is hoping that she can pretend to do both without anyone noticing.

As one of the keys to control of the Senate in 2020, Collins’s race will definitely be noticed.