Humana became the latest health insurer to serve notice that it might leave some Affordable Care Act exchanges next year, creating more uncertainty for customers ahead of this fall’s enrollment window and presidential campaign, during which the law is sure to remain a hot debate topic.

The insurer, which is being acquired by rival Aetna, said Wednesday that it expects to make a number of changes to its business for 2017, and that may include leaving some markets both on and off the exchanges or changing prices. Humana Inc. sold coverage in 15 states this year.

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