A progressive group in Utah that advocates government transparency and accountability filed a federal complaint against Representative Mia Love, a Republican, on Tuesday over alleged campaign finance violations, escalating the liberal fight against the vulnerable incumbent just seven weeks before November’s midterm elections.

Alliance for a Better Utah, a progressive nonprofit, filed the complaint with the Federal Election Commission and sent a detailed letter to the commission’s general counsel and the chief of the public integrity section at the Department of Justice’s criminal division. The letter, which comes after the commission forced Ms. Love to acknowledge that some of her primary funds had been improperly raised, argues that Ms. Love’s “actions are a betrayal of the public trust and of Utah voters,” and “should be subject to criminal penalties.”

In a statement, Ms. Love’s campaign called the complaint a political ploy.

“It is no surprise that an extremely liberal-leaning organization such as ‘Alliance for a Better Utah’ is filing a complaint on completely false and desperate charges,” said Sasha Clark, Ms. Love’s campaign communications director.

The crux of the allegation against Ms. Love stems from more than $1 million she raised leading up to her re-election campaign this year. Ms. Love did not face a primary challenger because of Utah’s convention nomination rules, but, according to the commission, she raised the money during the primary challenge period, and an additional $372,468 even after she secured the state nomination and knew a primary would not take place.