WASHINGTON, May 6 (Xinhua) -- Voters in the U.S. states of North Carolina and Indiana cast their ballots Tuesday, the latest critical day in the long-drawn Democratic presidential nomination race.

    The Democratic primary in Indiana is open to all voters, Democratic, Republican or independent.

    Senators Barack Obama and Hillary Clinton are the only two Democratic candidates on the ballot.

    The state has been allocated 84 delegates at the August 25-28 Democratic National Convention and 72 delegates are tied to the results of the primary.

    Polling started at 1000 GMT and will close at 2300 GMT, with the majority of the polling stations closing at 2200 GMT.

    Located in the midwestern region of the United States, Indiana is a diverse state with a few large urban areas and a number of smaller industrial cities.

    Unlike North Carolina, Indiana is a white-majority state, with African Americans accounting for just 9.42 percent of its population of 6.3 million.

    Polls show there Clinton has a slight edge over Obama in the state.