US Republican presidential candidate Donald Trump campaigned Saturday in the southern state of Virginia, where his Democratic rival, Kamala Harris, is leading the polls.

Just three days ahead of the vote, Trump's supporters packed the venue in Salem with a capacity of 7,000.

The former US president asked his crowd, "Are you better off now than you were four years ago?"

It was an apparent echo of the phrase used by Ronald Reagan in the closing weeks of his successful 1980 presidential campaign.

Trump also said it is going to be the most important election in US history.

Virginia is seen as a "blue state," where Democratic presidential candidates have won since 2008. An average of the latest polls suggests Harris is leading the state with 49.8 percent, while Trump has 44 percent.

In the final stage of the 2016 presidential race, Trump held rallies in Michigan and elsewhere, where his contender Hillary Clinton had been leading in the polls. This is believed to have helped him broaden his support and win the election.

Trump appears to be aiming to repeat the success of eight years ago.

Meanwhile, Vice President Harris on Saturday called for support in the battleground states of Georgia and North Carolina.

In North Carolina, Harris held a rally in Charlotte, the state's largest city. Her campaign said more than 10,000 people attended.

Harris pledged to listen to experts and people who disagree with her, because, unlike Trump, she doesn't believe people who disagree with her are the enemy. She added, "That's what real leadership looks like."

Harris also vowed to "always put country above party and self, and to be a president for all Americans."

Rock star Jon Bon Jovi also took the stage to show his support. He called on voters to cast their ballots, saying, "Now we can move forward together, embracing what makes us different."