(Reuters) - A federal judge on Thursday temporarily suspended a Michigan law that abolished straight-ticket voting - the practice of using one mark to vote for all candidates from one party - that was going to take effect in the November general election.

U.S. District Court Eastern District of Michigan Judge Gershwin Drain granted a preliminary injunction sought by civil rights and labor groups who sued Secretary of State Ruth Johnson arguing that the law would keep African-Americans from voting.

Johnson and Michigan Attorney General Bill Schuette will appeal the order on Monday or Tuesday next week, Schuette spokesman John Sellek said in an email.

In his ruling, Drain cited a report by Kurt Metzger, regional information specialist with the U.S. Census Bureau, that found that African-American voters are more likely to use straight-party voting than white voters.

The Michigan law is among a number of state voting rules that have been fought in the courts ahead of the November election, along with stricter voter identification laws in some states and laws on the voting rights of felons in others.

Drain said, "An injunction would protect the public against burdens on the right to vote." The plaintiffs in the case, the A. Philip Randolph Institute labor group and others, still have to go to trial to argue for a permanent injunction.

"This is a victory for the voters of this state. They have been able to vote a straight-party ballot for 100 years. Millions of voters use it. The judge said taking it away would deny people the right to vote," Mark Brewer, lawyer for the plaintiffs and a Michigan Democratic Party leader, said by telephone.

In January Michigan Governor Rick Snyder signed into a law a bill passed by the legislature to eliminate straight-party voting.

Proponents of the law say most states have moved away from the straight-ticket voting option. Removing the option forces voters to study candidates and encourages voters to make decisions based on criteria other than party affiliation.

Critics say straight-ticket voting is optional for voters, who can pick and choose candidates from different parties if they wish. They also said that the law was partisan because African Americans are more likely to vote Democratic.

Drain said the plaintiffs are likely to win their claim that the law violates the 1965 Voting Rights Act, because the law reduces voting opportunity for African Americans in the state.

(Reporting by Fiona Ortiz in Chicago; Editing by Cynthia Osterman)