Donald Trump's administration is sending $500 payments to nearly 1 million Americans this week, in a move that strategists say could potentially influence races that may ​determine whether his Republicans maintain control of Congress in the November midterm elections.

The White House says the payments are a refund for what it describes as excessive fees charged to people ‌who purchase health insurance through the Affordable Care Act.

The payments will not go out nationwide. Certain residents who live in the 30 states that rely on the federal HealthCare.gov marketplace to provide coverage will receive a check. Those who live in the 20 states that operate their own programs will not. While 19 million people rely on Obamacare, only 950,000 ​of them will get payments, according to the White House.

Democratic candidates and analysts call the payments a clear attempt to sway the election, ​but also say it is not enough to cover the increased costs voters have shouldered since Trump returned to office.