Sprinting to a dead heat?

The two election contenders are in a late sprint to ensure their supporters get out to the polls and to win over the dwindling pool of undecided voters in the eight or so battleground states where the election will be decided.

Obama and Romney remained in a statistical dead heat on Saturday in the daily Reuters/Ipsos online tracking poll. Obama led Romney by 47 percent to 45 percent, within the survey's credibility interval.

The poll also showed that support for the candidates was solidifying. Almost nine out of 10 of registered voters now say they will definitely vote for their candidate, leaving just 12 percent who say they could change their minds.

In contrast, an average of about 15 percent last week said they might still switch.

But more and more voters have already taken advantage of early voting programs and cast their ballots, despite the time remaining before Election Day. Eighteen percent of respondents in the Reuters/Ipsos poll said their votes were in.

The US election is not a true national poll, but a state-by-state contest in which 538 electoral votes are divided among the 50 states and Washington, DC, roughly according to population.

With the majority of states firmly Republican or Democratic, the fight for the "swing states" not firmly tied to either party is hugely important.

This year, there is a possibility one candidate could take enough states to win the electoral vote - and thus the White House - while trailing in the nationwide popular vote.

That last happened in the bitterly contested election of 2000, when Democrat Al Gore won half a million more votes nationally than Bush, but the Republican won the presidency because he ended up with more electoral votes.