Denver, Colorado  - Barack Obama is to accept the Democratic nomination for the presidency in a speech later Thursday, when he is expected to chart his plans for improving the weak economy and restoring the country's international standing.

Obama is the first African-American presidential nominee from a major party and his speech comes on the 45th anniversary of one of the most famous civil rights events in the country's history - Martin Luther King Jr's 1963 I Have A Dream speech.

Obama may briefly glance back on the long road travelled by American blacks since then, but most of his appearance will be devoted to his vision for the future.

A crowd of 75,000 is expected to be on hand at Denver's Invesco Field amidst tight security for the speech, breaking with tradition for acceptance speeches which are normally given within the smaller confines of the nominating convention hall. He is the first candidate to do so since John F Kennedy held his speech in another venue in 1960.

"We want to open up this convention to make sure that everybody who wants to come can join in the party," said Obama, who was formally nominated by the convention's 4,000 delegates Wednesday.

The party will include Olympic gold medal gymnast Shawn Johnson leading the Pledge of Allegiance. Musicians like Sheryl Crow and Michael McDonald will warm up the crowd.

Two of King's children will speak, as will civil rights stalwart John Lewis, a US congressman.

The stage has been designed to resemble the White House portico where US presidents are often pictured. The stadium will open at 1 pm (1900 GMT), hours before Obama's 8 pm (0200 GMT) speech.

Much of the first three convention days were devoted to filling in the blanks about Obama, 47, a relative newcomer on the national political scene, and healing the wounds of the bitter primary fight against Senator Hillary Clinton, 60.

In his acceptance speech, Obama is expected to look to the future.

"I think what Senator Obama wants to do is make sure everyone watching at home is going to have a clear sense of where he wants to take the country, that we're on the wrong path and Barack Obama is going to put us back on the right track both here at home and overseas," David Plouffe, Obama's campaign manager, told broadcaster ABC.

More than two-thirds of the seats at Mile High will be filled by residents of the Mountain West and Southwest regions, where Democrats hope to wrest away votes from Republicans.

Expectations are high for Obama's speech, his candidacy and possible presidency.

Stanley Crouch, an African-American columnist for New York's Daily News, noted that Obama has a "tall order" of tackling the country's crumbling education system and uncertainty on the foreign front.

"Can Obama force Americans to understand the gravity of our problems? Can he offer solutions?" he asked.

He called for Obama to "take off the gloves" and become a "dragon slayer whose sword has been forged in the intellectual smithy of thinkers."

"Barack Obama should offer more than a dream. Tonight, he should offer the American people real solutions that will free this country from its quagmire," Crouch wrote. (dpa)