Sen. Hillary Rodham Clinton (web|news|bio) won most of the delegates in West Virginia's Democratic primary Tuesday. Clinton added 20 delegates and Sen. Barack Obama (web|news|bio) won eight, according to an analysis of election returns by The Associated Press. All of West Virginia's delegates have been allocated. Tuesday's primary left Obama with a 166.5-delegate lead in the race for the Democratic nomination. He has 1,883.5 delegates, including endorsements from party and elected officials known as superdelegates. Clinton has 1,717, according to the latest AP tally.

The number of delegates needed to clinch the nomination increased by one Tuesday, to 2,026, with the election of Democrat Travis Childers to fill a vacant U.S. House seat in Mississippi. That increases the number of superdelegates to 797 and the overall number of delegates to 4,050.

Earlier Tuesday, Obama picked up four superdelegate endorsements, giving him 30 in the past week. At that pace, he will reach the number of delegates needed to clinch the nomination by the end of the primary season on June 3, when delegates from the five remaining primaries are included.

Obama now leads in states won, pledged delegates won in primaries and caucuses, and superdelegates.

On the Republican side, Sen. John McCain (web|news|bio) clinched his party's nomination March 4.

Nebraska also held presidential primaries Tuesday, but no delegates were at stake for Democrats or Republicans. Obama won Nebraska's Democratic caucuses on Feb. 9.

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 this summer.

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.

Written By STEPHEN OHLEMACHER

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