The US Democratic Party's rules committee has agreed a compromise to seat the delegates from the disputed states of Florida and Michigan.
Despite objections from supporters of Senator Hillary Clinton, all of the delegates will be seated and will be given half a vote each.
In a separate development, Senator Obama announced he is to leave his church, following the controversy involving his pastor the Reverend Jeremiah Wright.
Last night's compromise was reached after an occasionally rowdy day-long meeting of the Democratic Party's Convention Rules and Bylaws Committee.
The compromise will give Senator Clinton an additional 87 votes while Senator Obama gets an extra 63.
This still leaves Mr Obama ahead by almost 180 delegates.
The Clinton campaign wanted to block Mr Obama from receiving any of the votes from Michigan, where his name was not on the ballot.
Last night, Clinton campaign senior strategist Howard Ickes said Mrs Clinton had asked him to 'reserve her right to take this to the credentials committee' at the convention in Denver.
In a separate development, Senator Obama announced he is to leave the Trinity United Church of Christ in Chicago following the controversies involving his former pastor Jeremiah Wright and comments from a visiting Catholic priest at the church last week.