Hillary Clinton promised to be a champion for everyday Americans on Sunday as she kicked off a long-awaited second run for the White House as the commanding Democratic front runner.
"Everyday Americans need a champion. I want to be that champion," Clinton said in a video released on the internet that announced her run.
"Americans have fought their way back from tough economic times, but the deck is still stacked in favor of those at the top," she said.
Clinton, who lost a bruising Democratic nominating battle to Barack Obama in 2008, was expected to travel soon to Iowa, the state that holds the kickoff nominating contest in early 2016.
"It's official: Hillary's running for president," John Podesta, a top aide to Clinton, said in an email sent to supporters of her failed 2008 bid.
"She is hitting the road to Iowa to start talking directly with voters. There will be a formal kickoff event next month."
Clinton's campaign will emphasise her plans to address economic inequality and will tout the historic nature of her effort to become the first woman US president, aides said.
One of her biggest challenges will be to show a more down-to-earth side while connecting with ordinary voters.
Critics, including liberals in her own party, say she has grown out of touch after decades as the wife of former president Bill Clinton, a US senator and secretary of state.
In a memo made public on Saturday, Clinton's campaign manager, Robby Mook, told staff that while the goal was for Clinton to win the presidency, the campaign was not about her but about "everyday Americans."
"We are humble: we take nothing for granted, we are never afraid to lose, we always out-compete and fight for every vote we can win," he said in the campaign memo, titled "We Are Hillary for America."
Even before the much-anticipated announcement on Sunday, potential Republican opponents took swings at Clinton. Former Florida governor Jeb Bush criticized her guidance of US foreign policy as secretary of state.
"We must do better than the Obama-Clinton foreign policy that has damaged relationships with our allies and emboldened our enemies," Bush said in a video released by the political action committee Right to Rise.
Bush, brother to former president George W. Bush, is currently exploring a presidential bid.
Kentucky Senator Rand Paul, who formally began his campaign for the Republican nomination last week, made the rounds of Sunday talk shows to slam Clinton's handling of a 2012 attack on a US diplomatic compound in Benghazi, Libya.
In her memoir "Hard Choices," Clinton dismissed the Republican criticism of her handling of the attacks as exploiting a tragedy for political gain.
Hillary Clinton: A first lady with White House dreams