The race to be named Democratic candidate for the White House could still go to a nail-biting finish as hopefuls Barack Obama and Hillary Clinton remained finely balanced after the crucial 'Super Tuesday' poll.
In the Republican contest, John McCain moved closer to being named his party's candidate for the Oval Office with several key victories on the important night, which saw 24 states choosing their candidate for each party.
Meanwhile, the Democrat politician battling to become the first black president of the US took 13 states, although his rival Hillary won the three biggest prizes – California, her home state of New York and Massachusetts.
The Illinois senator was helped by a rousing endorsement from Meet The Parents star Robert De Niro.
"I've never made a speech like this at a political event before," revealed the Oscar-winner, speaking before a New Jersey rally. "So what am I doing here? I'm here because finally one person has inspired me. One person has given me hope. One person has made me believe that we can make a change."
In supporting Barack the actor becomes the latest in an ever-growing list of high-profile names to do so. Among those backing the 46–year-old politician are chat-show queen Oprah Winfrey, singer Stevie Wonder and John F Kennedy's daughter, Caroline Kennedy, who also turned out for the rally.