In Mississippi, Obama won 19 delegates and Clinton 14, according to an analysis of returns by The Associated Press.
Obama won the primary with more than 60 percent of the vote, according to unofficial returns. But Clinton was able to hold down Obama's delegate gains by winning one of the state's four congressional districts. Obama carried the other three.
Clinton eliminated the gain when she picked up delegates based on final results from the New York primary and the Colorado caucuses, both of which were held Feb. 5. Clinton gained four delegates in Colorado and one delegate in New York.
The results were delayed in New York because the race for one delegate was too close to call. Clinton won the New York primary, picking up 139 delegates, to 93 for Obama.
In Colorado, the Democratic Party did not release results by congressional district until this week. Ten delegates had been outstanding; three went to Obama and seven went to Clinton. Obama won the Colorado caucuses, getting 35 delegates, to 20 for Clinton.
Clinton also picked up three superdelegates Wednesday, but she lost a high-profile one when New York Gov. Eliot Spitzer resigned amid a scandal involving a high-priced prostitution ring.
New York's incoming governor, David Paterson, already is a Clinton superdelegate through his position as an at-large member of the Democratic National Committee.
In the overall race for the nomination, Obama had 1,602 delegates, including separately chosen party and elected officials known as superdelegates. Clinton had 1,497, according to the AP count.
It takes 2,025 delegates to secure the Democratic nomination at the party's national convention this summer.
The AP tracks the delegate races by calculating the number of national convention delegates won by candidates in each presidential primary or caucus, based on state and national party rules, and by interviewing unpledged delegates to obtain their preferences.
Most primaries and some caucuses are binding, meaning delegates won by the candidates are pledged to support that candidate at the national conventions.
Political parties in some states, however, use multistep procedures to award national delegates. Typically, such states use local caucuses to elect delegates to state or congressional district conventions, where national delegates are selected. In these states, the AP uses the results from local caucuses to calculate the number of national delegates each candidate will win, if the candidate's level of support at the caucus doesn't change.
