MINNEAPOLIS — President Donald Trump’s campaign attacked Minneapolis and its “radical leftist mayor” over an attempt to recover $530,000 in security costs for a rally in the liberal city, accusing the mayor of trying to sink the president’s event.

The campaign accused Mayor Jacob Frey — a Trump critic — of “conjuring a phony and outlandish bill for security” for Thursday’s rally that far exceeded that for a 2009 event in the same building by then-President Barack Obama.

The campaign said the city sent the estimate to Target Center’s operator, AEG Management, which threatened to cancel its contract to host the rally if the costs weren’t covered. Its law firm threatened to sue AEG if the rally doesn’t proceed.

Trump attacked Frey on Twitter on Tuesday, writing “Someone please tell the Radical Left Mayor of Minneapolis that he can’t price out Free Speech. Probably illegal!”

His campaign said the “bogus security charges” are an attempt to prevent Minneapolis residents from supporting Trump.

“The radical leftist mayor of Minneapolis, Jacob Frey, is abusing the power of his office and attempting to extort President Trump’s re-election campaign,” Trump’s campaign said in a statement.

The rally, Trump’s first since the House moved toward impeachment over his handling of a phone call with Ukraine’s president, is in a state Trump nearly won in 2016 and has talked frequently of capturing in 2020. But it takes place in a traditionally liberal city and the home turf of a frequent foil, Democratic Rep. Ilhan Omar.

When the rally was announced last month, Frey said Trump’s “message of hatred” would never be welcome in Minnesota. But at a news conference Tuesday, he said the city will do all it can to guarantee a “safe and peaceful week,” regardless of his political differences with Trump.

Frey stood by the security costs estimate, saying a Trump political rally brings “significant expenses” not associated with Obama’s 2009 event, which was aimed at building support for health care reform. Frey said the Trump campaign’s complaint is with AEG.

Neither AEG nor the law firm for Trump’s campaign immediately responded to messages seeking comment.

Trump also attacked Frey over Twitter for a policy that prohibits city police officers from wearing their uniforms in support of candidates at political events or in campaign ads. The city’s police union spokesman has complained about the policy, and the union is selling “Cops for Trump” T-shirts.

Frey said the police force must be nonpartisan and non-ideological.

“They’re free to express their First Amendment rights but should do so off-duty,” he said.