Scarlett Johansson was given a standing ovation as she delivered a rousing speech in support of U.S. President Barack Obama at the Democratic National Convention on Thursday.

The leader is campaigning for re-election in November, and several star supporters headed to the rally in Charlotte, North Carolina in a bid to boost his chances of returning to the White House for four more years.

Ashley Judd, America Ferrera and James Taylor were among the stars who backed Obama in news interviews from the DNC throughout Thursday, while Taylor, Mary J. Blige and Foo Fighters also performed.

You know who I'm voting for. I'm not gonna tell you who to vote for; I'm here to ask you to commit to vote. It's never been easier than now. Vote so that your voice is heard.

The rockers kicked off their set with their hit My Hero, and frontman Dave Grohl told the crowd, "It's an honour to be here and I think this song makes perfect sense here tonight".

Actress Kerry Washington was among the speakers, and she told the audience, "I'm here not just as an actress, but as a woman, an African-American, a granddaughter of an immigrant who came through Ellis Island, a person who could have not afforded college without the help of student loans and as one of millions of volunteers working to re-elect President Obama.

"So many people have struggled so that you and I, all of us, could have a voice in this great democracy and live up to those first three words of our constitution - We The People. We cannot sit on the sidelines. I get it - whether it's school, work, family, we've all got a lot on our minds... but here's the thing - you may not be thinking about politics but politics is thinking about you".

Johansson then took to the stage, and reminisced about her childhood and how benefits helped her family before calling for young Americans to make sure their votes count in November. She told the crowd, "I grew up in New York City, I grew up with four siblings, my father barely made enough to get by.

We moved every year and finally settled in a housing development for lower-middle income families.

We went to public schools and depended on programs for school transport and lunches, as did most of my friends.

"In 2008, less than half the eligible voters between the ages of 18 and 24 voted... Young America, why are we only speaking with half our voice when so many issues at stake here directly affect us?

"You know who I'm voting for. I'm not gonna tell you who to vote for; I'm here to ask you to commit to vote. It's never been easier than now. Vote so that your voice is heard.

"When I was a little girl, my mother - she's a registered Democrat - she would take me into the polling booth and tell me which buttons to press and when to pull the lever. Is that even legal, I don't know, I don't think so! I remember that excitement I felt in that secret box... This last election, I finally got to punch those buttons for real. I was so excited I wore my 'I voted' pin the whole day, it was my finest accessory".

Applause for Johannson rang out as she added, "And this year, on November 6th, I am filled with that same pride, that same enthusiasm, to press the button to re-elect President Barack Obama. So get out there, exercise your right to vote".