After black voters in South Carolina deserted her for Barack Obama, Hillary Clinton has invoked icons Nelson Mandela and Martin Luther King while preaching racial unity.
African Americans, a key Democratic constituency, went overwhelmingly for the Illinois senator in Saturday's primary vote -- in a stunning rebuff for Clinton, and her husband, ex-president Bill Clinton.
The defeat came after both camps accused the other of taking the campaign onto dangerous racial territory, as Obama strives to become the first black US president.
Clinton opened her fightback by stressing unity, worshipping in a black Baptist church in Memphis, where civil rights icon King was gunned down in 1968, alongside Reverend Samuel "Billy" Kyles, who was with him when he died.
"I think we are being called again," said Clinton, who had earlier appeared moved at her welcome, as she sat in a straight-backed chair at the front of the church, rocking her head, as a Baptist choir chanted soaring hymns. "I believe that Dr King glimpsed ... What was possible," Clinton said on Sunday.
"It was about whether, we inside our hearts, saw what was possible for ourselves and others," said the former first lady, who often mentions how she, as a teenager, saw King speak.
Clinton went on to relate one of the "most transformative experiences" of her life, getting to know Mandela after leading the US delegation to his inauguration as the first post-apartheid president of South Africa.
She told how he had asked his three former jailors to stand during the ceremonies, and paid tribute to them for offering him a glimpse of humanity during his incarceration.