Republican lawmakers in Tennessee gave final approval on Monday to an aggressive plan to split Nashville, a Democratic bastion, in a deeply Republican state, into several congressional districts as part of an effort to tilt the state’s congressional map in their favor. The plan is now waiting for approval from Governor Bill Lee, who is likely to sign it.

Nashville currently sits in the state’s fifth congressional district, represented by Jim Cooper, a Democrat who has held the seat for nearly 20 years. It’s a solid Democratic district – Joe Biden carried it by nearly 24 points in 2020 – but on Tuesday, Cooper announced he was retiring from Congress.

“Despite my strength at the polls, I could not stop the general assembly from dismembering Nashville. No one tried harder to keep our city whole,” he said in a statement. “I explored every possible way, including lawsuits, to stop the gerrymandering and to win one of the three new congressional districts that now divide Nashville. There’s no way, at least for me in this election cycle, but there may be a path for other worthy candidates.”

The new districts crack the concentration of Democratic voters in Nashville and cram them into three districts that stretch across the state and are filled with reliable Republican voters. Donald Trump would have easily carried all three of the proposed districts in 2020. The plan is one of the clearest, and most brazen, efforts to dismantle a Democratic district to benefit Republicans.

Cooper, who has served in Congress for more than three decades in total, told the Guardian the plan was “an outrage”.

“It’s just raw politics,” he said. “They’re trying to fix something that isn’t broken.”

Republican leaders in the state legislature have defended the plan by saying it would be good to have multiple people represent Nashville in Congress. “I’ve never bought into the approach that having multiple people represent a big city is bad thing,” Cameron Sexton, the Republican speaker of the Tennessee house of representatives, told the Associated Press.

Odessa Kelly, a progressive Nashville activist who has already launched a campaign for the seat Cooper holds, said the Republican-drawn proposal made her “livid.”

“To have someone just disregard your humanity, disregard democracy and just stomp on everything that this country is supposed to stand for, just because they have a personal interest to have a power grab, is one of the most racist and egregious acts that I’ve ever experienced,” she said. “This is the type of thing that you sound the alarm about.”

The proposed plan would clearly diminish the influence of Black voters and other voters of color concentrated in Nashville, inserting them into districts that are overwhelmingly white and Republican. About a quarter of the eligible voting population in the fifth congressional district is Black. Under the new lines, Black voters would make up about 14% of the new fifth district and about 17% and 10% of the other two new districts in the city.

Cooper agreed that the maps would significantly reduce the influence of minority voters. “At most it will be tokenism,” he said.

Tequila Johnson, a co-founder and vice-president of the Equity Alliance, said: “We see that as racism, as an intentional effort to dilute the voting power and the voting voice of Black people in Nashville. It was a lack of representation that would have a “ripple effect”, added Johnson, whose organization is focused on mobilizing Black voters.

“We’re less likely to have a relationship with our congressperson. The people who are going to be representing Nashville don’t live in Nashville, don’t understand what the needs are in Nashville,” she said.

Regardless of which lines end up in place, Johnson said her group would continue to mobilize voters and reach out to voters outside of Nashville.

“We are using this as an inroad to build relationships with our rural neighbors,” she said. “We’re going to make sure that the area that you’re lumping us into where they have hospitals closing, where they aren’t able to afford certain amenities for children, buses and enough teachers, things like that, we’re going to go out there and organize and have conversations with them and make sure that they know the reason they don’t have those things.”

This article is part of the Guardian’s series The Fight to Vote