US presidential hopefuls from the Democratic camp Barack Obama and Hillary Clinton as well as Republican warhorse John McCain on Monday launched their last frenzied day of campaigning to swing voters in their favour ahead of the make-or-break 'Super Tuesday' showdown in 24 state primaries.
Pollsters predicted a tight race between Clinton and Obama, while McCain looked set to take a firm grip over rival Mitt Romney. "Super Tuesday" states account for over half the delegates who go to party conventions to formally choose the nominees to run in November's election.
A national poll for the Washington Post and ABC showed Clinton's lead over Obama had narrowed to 4 per cent, while other polls showed the two neck and neck in the key state of California.
Of the 2,025 delegates needed to secure the nomination as the Democratic Party's presidential candidate, California carries 370.
The same national poll showed McCain well ahead of all his rivals. The Arizona senator had 48 per cent against Romney's 24 per cent, with Mike Huckabee and Ron Paul trailing far behind.
Obama, buoyed by the South Carolina victory, is looking to close the gap with Clinton in the Tuesday poll in 22 states with more than 1,600 delegates at stake. on sunday Obama and Clinton were courting each other's core constituencies - black voters and women, respectively - as they rallied for an edge.