Michelle Obama promised the Americans and the world on Monday that her husband Barack Obama would be an "extraordinary president". She reassured the voters that Obama shares their bedrock values and belief in the American dream and would like to give every child a chance to fulfill his dream.

"Barack and I set out to build lives guided by these values, and pass them on to the next generation," she said in extracts released before her appearance at the Democratic National Convention.

"I come here as a wife who loves her husband and believes he will be an extraordinary president," said Mrs. Obama in the remarks released ahead of her opening night keynote speech at the Democratic National convention here.

"I come here as a mom whose girls are the heart of my heart and the center of my world," said Mrs. Obama who is a mother to two young daughters, Malia and Sasha.

"We want our children and all children in this nation, to know that the only limit to the height of your achievements is the reach of your dreams and your willingness to work for them," she said.

The speech was to be delivered in front of approximately 4,400 delegates at the opening night of the Democratic Party convention, all prepared to nominate Barack Obama, 47, as the country's first black presidential nominee.

She further spoke of their personal lives and all the hardships that they have faced so that the common man is able to relate to Obama in some way or the other.

"Nobody in the world knows Barack Obama better than his wife Michelle," Obama spokesman Josh Earnest said earlier Monday. "Her personal perspective and what she offers will, I think, be very compelling to the American public."