Washington, Nov 4 (IANS): Before the polls for the US presidential election close in Pennsylvania, one of the key battleground states, Governor Tom Wolf has urged residents to "remain calm".

"Across the state, dedicated county workers are ready to tirelessly make sure everyone's vote counts," CNN quoted Wolf as saying in a video message.

"But counting that tremendous number of ballots will take more time than we are used to. We may not know the results today, but I encourage all of us to take a deep breath and be patient.

"What is most important is that we have accurate results, even if that takes a little longer," he added.

In Pennsylvania, where the two candidates spent the weekend campaigning in a last-ditch efforts to garner votes, an NBC News-Marist poll released on Monday placed Biden ahead with a 5-point lead, 51 per cent to 46 per cent.

Meanwhile, the RealClearPolitics polling average gave the former Vice President a 4.3 percentage point lead over the President.

But the state's results won't be immediately due to the large number of early and mail-in votes that have already been cast.

Besides the Trump-Biden race, all 435 seats in the US House of Representatives and 35 of the 100 seats in the Senate were also be in the fray on Tuesday.

More than a dozen state and territorial governorships, among many other state and local posts, will also be contested.