Two civil rights groups have asked the Justice Department to investigate an election in which they say voting machine problems prevented as many as 58,000 voters, many of them black, from casting ballots.

New Orleans, where nearly 70 percent of voters are black, was the only part of the state where voting machines were not delivered on time in the Sept. 18 election. Voters cast ballots in a number of local elections, plus on a statewide constitutional amendment to ban same-sex marriage.

The NAACP and the Association of Community Organizations for Reform Now (ACORN) said in a letter to the Justice Department that a federal investigation is required "in light of possible violations" of the Voting Rights Act.

"Our concerns are that we have been closed out of the election process for so long and we don't want anything else to thwart it any further than it already has been," said Beulah Labostrie, president of the Louisiana chapter of ACORN. "We, particularly in the African American community, do not want any obstruction in the ability for all to vote."

A message left for a Justice Department spokesman was not returned Friday.

The city's clerk of court has accepted blame for the problems, which happened on the weekend after much of the city was evacuated for Hurricane Ivan. Truck drivers hired to deliver the machines to polling places either did not deliver them or were unable to get the machines into the voting sites on time.

The clerk, Kimberly Williamson Butler, who is black, apologized Thursday and said she would work with Secretary of State Fox McKeithen to ensure the Nov. 2 election goes smoothly.

McKeithen, the state official responsible for elections, said he had no problems with a federal investigation but noted he and the state attorney general have already started a probe.

Polls opened at 6 a.m. in the election, but some voting sites did not have machines until 3 p.m. Polls closed at 8 p.m.

Louisiana voters overwhelmingly approved the constitutional amendment that would ban same-sex marriages and civil unions.