In a conference call with reporters, top officials of President Barack Obama's campaign insisted that they were building a lead in key states that Romney would have difficulty overcoming.
"Our opponent is losing among early voters in nearly every public poll in every battleground state," Jeremy Bird, the Obama campaign's field director, said yesterday.
Romney would have to win the election-day vote with majorities as large as 60 per cent in some states in order to prevail, Bird said, citing polling figures.
So far, Democratic voters outnumber Republicans in Florida, Iowa, Nevada, North Carolina and Ohio