JAY-Z has thrown his weight behind Barack Obama as he attempts to gain a second term as President of the United States.

The 99 Problems rapper has released a new video called The Power of Our Voice that encourages Americans to remember why they voted for Obama as their President four years ago.

"When the president got in office initially, what he represented to a nation of kids was hope ... the hope of people across the country who would look and see themselves and know the possibilities," Jay-Z says.

"For so long, there was this voice that was silenced out there as far as exercising your right to vote. I think it was a voice that was silent because people had lost hope. They didn't believe that their voice mattered or counted."

"Now people are exercising their right, and you are starting to see the power of our vote. He (Obama) made it mean something for the first time for a lot of people."

Jay-Z also helped Obama during his 2008 election campaign.