Former US President Donald Trump on Wednesday is cruising towards winning the race for the White House in one of the greatest political comebacks in American history by almost defeating his Democratic rival Kamala Harris in an election that virtually divided the country into two camps.

"This will be the golden age of America... America has given us an unprecedented mandate" Trump said in West Palm Beach in Florida, in a victory speech.

He told Americans that this moment will "help this country heal".

According to projections, Trump is all set to receive 270 electoral college votes blocking Harris' chance to win the polls.

The 78-year-old Republican leader is winning the battleground states of Pennsylvania, Georgia and North Carolina, the three crucial battleground states. However, the Associated Press (AP) has called the race in favour of Trump in these states.

According to races called by the Associated Press up to 1 pm, 267 electoral votes had gone to Republican candidate Trump and 214 to Democratic Party's Harris.

Counting of votes is still underway in other battleground states of Arizona, Michigan, Wisconsin and Nevada.

The US has 50 states and most of them vote for the same party in every election except the swing states.

Generally, there is not much surprise over the candidates picking up victories in states other than the pivotal battleground ones. Overall a total of 538 electoral college votes are up for grabs.

If both candidates register victory in all the states that historically support the same party, then it will leave Harris 44 electoral college votes short of victory and Trump 51 votes short.

The swing states of Pennsylvania, Michigan and Wisconsin, known as part of the Rust Belt, have been traditionally the strongholds of the Democratic Party.

Earlier, exit polls showed state of democracy, the shape of the economy and abortion are the most important issues for American voters in the election.

Almost six in 10 people ranked the state of democracy as their number one issue, according to exit polls released by CBS News.

It was followed by abortion as five per cent of the voters felt it was an important issue for them.

Over one in 10 chose the economy as a priority issue.

An exit poll by CNN said roughly three-quarters of the electorate holds a negative view of the way things are going in the US today.

Only about one-quarter call themselves enthusiastic or satisfied with the state of the nation, with more than four in 10 dissatisfied and roughly three in 10 saying they are angry, according to the poll.

Voters remain generally optimistic, with more than 6 in 10 saying that America’s best days are in the future, and only about one-third that they're already in the past, the CNN poll found.