(Reuters) - A U.S. appeals court on Wednesday rejected Michigan's bid to reinstate its ban on straight-party voting, a ruling that means voters in the state will be able to use one mark to select all candidates from one party in the Nov. 8 general election.

A three-judge panel of the 6th U.S. Circuit Court of Appeals in Cincinnati ruled unanimously to uphold an injunction issued by a federal judge in July that temporarily suspended Michigan's law that abolished straight-ticket voting.

The matter remains pending before the federal courts for a definitive ruling.

Michigan's is one of several legal battles over state voting rules ahead of the November election, including stricter voter identification laws in some states and laws on the voting rights of felons in others.

African-American voters are more likely to use the straight-party option on the ballot than white voters, according to civil rights groups who had challenged the new Michigan law abolishing the 125-year-old practice.

Most states have abolished straight-party voting, and proponents of Michigan's law said that removing the option forces voters to study candidates more thoroughly.

But critics of the law argued that straight-ticket voting is optional. Voters can pick and choose candidates from different parties if they wish. They also said the law was partisan because African Americans are more likely to vote Democratic and to use the straight-ticket option.

Civil rights and labor groups sued Michigan's Secretary of State Ruth Johnson and Attorney General Bill Schuette to have the straight-ticket voting option reinstated.

U.S. District Court Judge Gershwin Drain granted the plaintiffs an injunction, saying the elimination of the straight-ticket option would be a burden on the right to vote, and would cause confusion and long wait times at polls.

Johnson and Schuette appealed, trying to have the ban reinstated.

In their Wednesday ruling, the appeals court judges upheld Drain's decision.

(Reporting by Fiona Ortiz; Editing by Jonathan Oatis)