Clinton tries to tap Beyonce's BeyHive

Beyonce's backup dancers were wearing Hillary-blue pantsuits when Queen B and husband, rapper Jay Z performed at a free concert to woo young voters.

Beyonce's backup dancers were wearing Hillary-blue pantsuits during a concert to woo young voters. (AAP) Source: EPA

The lights were bright. The beats were pumping. And the backup dancers were wearing blue pantsuits.

After raucous performances from Beyonce and her husband, rapper Jay Z, Hillary Clinton had one simple message for the packed, cheering crowd at Cleveland's Wolstein Center: "Help us win Ohio."

Clinton's campaign is turning to a series of free concerts to appeal to young and minority voters not necessarily motivated to vote for her. Beyonce and Jay-Z offered their own testimonials to the woman who, if elected, would be the country's first female president and follow its first black president.

Beyonce noted that less than a century ago, women did not have the right to vote.

"Look how far we've come from having no voice to being on the brink of history - again," Beyonce said. "But we have to vote."

The singer says she was thrilled that her young nephew was able to witness Barack Obama's 2008 election as the nation's first black president.

Now she wants her daughter "to grow up seeing a woman lead this country and know her possibilities are limitless," Beyonce said. "That's why I'm with her."

A series of hip-hop stars were part of the show, including Big Sean, J. Cole and Chance the Rapper, who encouraged the crowd to vote for Clinton - at the very least just to prevent Donald Trump from winning the White House.

"His conversation is divisive," said Jay Z. "He cannot be our president"

Big Sean recalled being in the audience eight years ago when Jay Z hosted a similar free event for Obama's campaign in 2008.

Now, he told the cheering audience, "we with her."

At one point, Clinton's famous quote that she "could have stayed home and baked cookies" flashed on the big screens. At another, the slogan "bad officials are elected by good citizens who do not vote" was blasted to the crowd.

Clinton offered her own praise for the show. "I am so energised after this concert and I have to say: Didn't you love the pantsuits?"