Beyonce has expressed her "respect and adoration" for incumbent U.S. President Barack Obama in a touching open letter on the eve of the 2012 election.

As her rapper husband Jay-Z joined the Democrat leader on the campaign trail for a final push for votes on Monday, the Crazy In Love hitmaker picked up a pen and paper and shared her admiration for Obama with fans online.

You are the leader to take us from where we are to where we need to be. You are the reason my daughter and nephew will grow up knowing that they can truly be ANYTHING they want to be.

In the message, which has been posted on her website, Beyonce writes, "President Obama, Everyday we see your heart and character, inspiring all of us to give more of ourselves.

"You are the leader to take us from where we are to where we need to be. You are the reason my daughter and nephew will grow up knowing that they can truly be ANYTHING they want to be.

"All my respect and adoration, Beyonce".

The singer, who recently hosted an Obama fundraiser with Jay-Z in New York, has previously penned a similar note to the politician's wife, First Lady Michelle Obama, hailing her as the ultimate African American role model for her young daughter, Blue Ivy.

Americans will head to the polls on Tuesday.