As opinion polls suggest Donald Trump is gaining support, Hillary Clinton has been holding rallies in states that had been considered safe for the Democrats.
BBC reports that both teams are now concentrating more on getting their supporters to vote rather than swaying those undecided.
Thirty-seven million early ballots have already been cast.
Meanwhile, US authorities say they are assessing the credibility of information on a possible Al-Qaeda terror attack.
New York, Texas and Virginia are believed to be the potential targets mentioned in connection with a possible attack before Election Day on Tuesday, but a police spokesman said the information “lacks specificity”.
Officials say they regularly assess all possible threats before major events.
News of a possible attack came as both Clinton and Trump made final pushes for support in battleground states across the US.
They both held rallies in Ohio and Pennsylvania, two states that may prove crucial on Tuesday.
National polls have suggested that the Republican candidate has gained substantial ground on his rival in the last week or so.
That momentum also appears to have helped him in several key battleground states.
BDST: 1537 HRS, NOV 05, 2016
NJ/SR