Defeated Democratic presidential candidate Hillary Clinton has urged Democrats to unite behind Barack Obama, calling herself a "proud supporter" of the presidential candidate.
Seeking to ease doubts that she would fight hard for Mr Obama after a long and bruising contest between the pair, Mrs Clinton told the Democratic National Convention on Wednesday that it was time to unite as a single party with a single purpose.
She told delegates Mr Obama was her candidate and he should be president.
Earlier in the day, law enforcement officials in Colorado played down reports of an assassination attempt against Mr Obama.
Four people have been arrested and charged with drugs and firearm offences after police seized two rifles, a scope, walkie-talkies and boxes of ammunition.
A television station in Denver reported that one man had claimed the group was going to try to shoot Mr Obama from a high vantage point.
Mr Obama is due to accept his party's nomination for president in an open-air football stadium later in the week, making him the first African-American nominee for president.
But a United States attorney in Denver, Troy Eid, says there was no credible threat to Mr Obama, the Democratic National Convention or the people of Colorado.
The presidential vote will be held on 4 November. Mr Obama is running against Republican candidate John McCain.