Former Tallahassee Mayor and gubernatorial candidate Andrew Gillum is urging U.S. Senators to reject the confirmation of a controversial nomination to the Eleventh Circuit Court of Appeals.

Gillum and some civil rights activists oppose Alabama District Court Judge Andrew Brasher’s confirmation, who is up for a vote in the full Senate as soon as Tuesday. The Eleventh Circuit handles appeals from cases in Georgia, Florida and Alabama.

The groups oppose Brasher because of his past positions on voting rights, LGBTQ equality and reproductive rights and contends he argued in favor of racial gerrymandering. They also argue he has worked to undermine environmental protections. They also point to his involvement in an Alabama lawsuit making the case that undocumented people shouldn’t be counted in the Census.

Gillum said he’s concerned about the fate of Amendment 4, which restored voting rights to felons once they complete the terms of their sentences. A three-judge panel on the Eleventh Circuit heard arguments last month in a lawsuit civil rights groups filed over legislation Republicans passed (SB 7066) last year requiring the former inmates to satisfy all financial obligations before regaining the right to vote.

“It is a cause that is very close to my heart,” Gillum said. “We know that if we don’t win this case, more than 1 million citizens in the state of Florida will be prevented from voting and participating in the 2020 presidential election.”

If the Senate confirms Basher, President Donald Trump will have appointed six judges to the court. Gillum worries that could jeopardize the Amendment 4 case on which the court is expected to make a ruling. Appellants can ask for a hearing before the full court, which means the new appointee could have a say in the case.

Brasher also declined to say whether Brown v. Board of Education was correctly decided. The Supreme Court ruled in that case school segregation was unconstitutional.

The Senate confirmed Brasher to the Middle District of Alabama last May on a 52-47 party line vote. Trump nominated him for the appeals court in November.

The American Bar Association rates Brasher well-qualified. He is the former solicitor general of Alabama. Brasher is a member of the Federalist Society.