By Jon Herskovitz

AUSTIN, Texas (Reuters) - Texas reached a deal with civil rights groups to remedy a voter identification law that a U.S. appeals court last month ruled was discriminatory and violated the U.S. Voting Rights Act, court papers filed on Wednesday showed.

Texas had been ordered by the U.S. Court of Appeals for the Fifth Circuit to work out a fix ahead of the November general election to the law that required voters to show government-issued IDs such as a driver's license, passport or concealed handgun license before casting a ballot.

The agreement is unlikely to affect the Nov.8 presidential election, given Texas is a longtime Republican stronghold, but could influence local races in the state if more people cast votes.

Plaintiffs - including a coalition of civil rights groups - had argued the existing law could exclude as many as 600,000 voters, mostly racial minorities and the impoverished who could not obtain the appropriate identification.

Under the deal, which still needs to be approved by a federal judge, a voter whose name appears on the voting roll but is without the appropriate ID could vote after showing an item such as a valid voter registration card or a government document that displays the voter's name and address.

The voter would also have to sign a declaration swearing that he or she has had a reasonable difficultly that prevented obtaining one of the accepted forms of photo identification.

Critics of the voter ID law said it, and similar statutes that have been passed in Republican-governed states, were intended to make it harder for minorities such as African-Americans and Hispanics, who tend to support Democrats, to vote.

Supporters of these laws have said they are necessary to prevent voter fraud.

The office of Texas Attorney General Ken Paxton, a Republican, said it reached the deal due to the court's time constraints and it planned to appeal the decision to the U.S. Supreme Court.

In recent months courts have struck down voter ID laws in states including Wisconsin, North Carolina and North Dakota, saying the measures were a form of discrimination against racial minorities.

In North Carolina, the decision to strike down such a law could have an impact in the state where Democratic presidential nominee Hillary Clinton is in a tight battle with Republican nominee Donald Trump.

Trump is expected to win Texas but the shift in the voter ID law could affect four or five local races, said Mark Jones, a professor in political science at Rice University in Texas.

(Reporting by Jon Herskovitz; Editing by Leslie Adler and Andrew Hay)