Voters on Guam were choosing the island's four delegates to assist in selecting the Democratic Party's candidate for the U.S.'s November presidential elections.
Obama received 2,264 votes while Clinton took 2,257. They will now split the delegates. Neither candidate campaigned in Guam, but in a race where every vote counts, both of them set out their respective case in a series of radio interviews.
Guam, which has been a U.S. territory since 1898, has a population of less than 175,000.
Victory for Obama means he slightly increases his lead over Clinton in the race for the Democratic Party nomination to run against Republican John McCain in the November election. However, it looks unlikely that either candidate will be able to clinch victory without the assistance of the so-called 'super-delegates' - top party members and other influential figures who are free to back any candidate.
The nomination contest now moves to North Carolina and Indiana on May 6. Between them, the two states have a total of 187 delegates.
