WASHINGTON, May 6 (Xinhua) -- Voters in North Carolina and Indiana are casting their ballots Tuesday in the latest critical race for the Democratic presidential nomination.

    In North Carolina, polling hours run from 1030 GMT to 2330 GMT while in Indiana, voting started at 1000 GMT and will close at 2300 GMT.

    There are 72 convention delegates at stake in Indiana and 115 in North Carolina.

    Pre-election polls show Barack Obama is likely to win in North Carolina but Hillary Clinton has the edge in Indiana.

    The Washington newspaper Politico suggests there are several things to watch out for in the Indiana primary.

    First is the turnout. Analysts are expecting far bigger turnouts this year than in 2004, when about 22 percent of voters cast their ballots in the presidential primary.

    A much bigger turnout is good news for Obama because it means those who have not been politically engaged in the past are coming out.

    If that does not happen, it will work in Clinton's favor.

    Second, a crucial factor will be the preferences of the more than 200,000 new voters who were added to the registration rolls.

    Third, places to watch out for are Indianapolis in central Indiana and Gary's Lake County in the northwest corner, which is part of the Chicago media market.

    Both areas boast significant African American populations. It will be a good night for Obama if he can win by 10- to 20-point margins in both areas.

    For Clinton, she must rely on the Ohio River towns in southern Indiana along the Kentucky border and east central Indiana.