WASHINGTON – Minneapolis police officers rankled by a new department policy barring off-duty staff from wearing their uniforms to political events plan to instead swarm President Donald Trump's rally Thursday with a "sea of red" specialty T-shirts.

The policy change came the day after Trump announced he would host a rally in Minneapolis. The head of the local police union argues the ban was a political move meant to favor the city's Democratic officials. The police department for its part says the policy is about avoiding the appearance of political bias.

But the person who could be most irked by the rule change? The president, who is traveling to Minneapolis on Thursday for his first campaign rally since House Democrats announced an impeachment inquiry against him.

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Trump often surrounds himself with men and women in uniform, both in the White House and on the campaign trail. He has has long painted himself as a pro-law enforcement president, ranging from his sharp criticism of NFL player protests during the national anthem over police brutality to the Department of Justice's slowed pace of civil rights investigations into local police departments.

In February at the Major County Sheriffs and the Major Cities Chiefs Association Joint Conference, he renewed his commitment to law enforcement, vowing to make "officer safety a top priority."

"In my administration, we understand that reducing crime begins with respecting law enforcement. We will not tolerate smears, or slanders or assaults on those who wear the badge and police our streets," he said.

And that support appears to be reciprocal. He earned the endorsement of the National Fraternal Order of Police, which claims more than 330,000 members, in 2016. And the International Union of Police Associations (IUPA) has already endorsed him in his 2020 re-election bid.

But instead of the thin blue line appearing behind Trump on Thursday, there will be "a sea of red T-shirts," said Lt. Bob Kroll, president of the Police Officers Federation of Minneapolis. The shirt features the phrase "Cops for Trump" emblazoned across an American flag in the shape of Minnesota and will be sold online and at the rally. All proceeds from the shirt sales will go to the union's charity, Kroll said.

Trump weighed in on the back-and-forth Tuesday on Twitter, thanking Kroll and adding that he plans to take some of the police T-shirts back to Washington.

How we got here

The T-shirt sale follows furor over a new Minneapolis Police Department policy that prohibits off-duty officers from wearing their uniform to political events.

The policy, according to police spokesman John Elder, is to prevent officers from showing political bias.

"The uniform gets translated back to the average person as someone being from the police department," he said. "It's very confusing for people when they see someone in uniform to understand the difference between the city and the federation."

But Kroll said politics are behind the rule change and said he was not surprised when the police chief called him to inform him of the new policy. He pointed to comments made by Minneapolis Mayor Jacob Frey following the announcement of the Trump rally, in which Frey said Trump's "message of hatred will never be welcome in Minneapolis."

“Under ordinary circumstances, it would be an honor to welcome a sitting President of the United States to Minneapolis and to showcase all our city has to offer on the national stage," Frey said in a statement. "But these aren’t ordinary circumstances. Since taking office President Trump’s actions have been reprehensible and his rhetoric has made it clear that he does not value the perspectives or rights of Minneapolis’ diverse communities."

Elder and Frey maintain officials have been preparing the rule change for months, well before Trump announced his rally.

Kroll said the timing of the uniform rule change appeared to be "very conspicuous."

"The president holds a lot of purse strings that our citizens could completely benefit from and it's just irresponsible for the mayor to make a statement like that," he said.

Trump lashed out at Frey on Twitter Tuesday, calling him a "lightweight" and accusing him of trying to block the visit by overcharging the Target Center $530,000 for security costs related to the event.

The Target Center told the Trump campaign it had to pay the security fees imposed by the city or it couldn't use the venue. The campaign threatened to sue the Target Center's parent company, AEG Management, and said the company would be in breach of contract if it did not let Trump hold his event.

Frey quickly responded on Twitter, saying "Yawn...Welcome to Minneapolis where we pay our bills, we govern with integrety, and we love all of our neighbors."

Critics were quick to point out the Trump campaign has left other cities to foot the bill after a rally or event. The Trump campaign has yet to reimburse officials in El Paso, Texas, about $500,000 in costs related to a rally he held there in February.

Attendance at Obama event

Members of the local union were outraged when they learned they couldn't wear their uniform to the rally, Kroll said, noting they had been ordered to appear at past presidential visits, including one by President Barack Obama in 2013.

But while Obama did appear against a backdrop of uniformed men and women in Minneapolis in February 2013, it was for a presidential event on gun control measures and not a political rally.

That's a key difference, according to Chuck Wexler, executive director of the Police Executive Research Forum, who said it's not uncommon for police departments to ban their officers from dressing in uniform at a campaign event.

"When they wear their uniform, they're representing their departments, they're not representing themselves," he said. "If they're not working, most departments would prohibit them from wearing their uniform to a political rally."

Kroll argues the policy underscores the political divide between officials in Minneapolis, a Democratic stronghold, and local officers who may skew more Republican.

He and other officers came under scrutiny in 2018 when they appeared in a campaign ad with former Republican Gov. Tim Pawlenty, who promised to crack down on immigration. Mayor Frey and other officials criticized the ad, noting the officers' appearance conflicted with Minneapolis status as a "sanctuary city."

“This is the party that preaches are all welcome here," Kroll said of Minnesota's Democratic-Farmer-Labor Party, the local Democratic party. "They’re supposed to be accepting of all – except Republicans."