Democratic vice presidential candidate Tim Kain speaks to the Progressive National Baptist Convention in New Orlean slast week. (AP/Gerald Herbert)

ASHEVILLE, N.C. — Tim Kaine, the Democratic vice presidential nominee, cautioned Monday against his party becoming overconfident in the wake of polls showing his running mate, Hillary Clinton, opening a lead over Republican Donald Trump in several battleground states, including North Carolina.

“This is going to be a close race, I predict,” Kaine said at a rally here. “We’re doing really good in some polls right now. … But you’ve just got to remember, this has been a season of surprises.”

Kaine, making his second trip to the Tar Heel State this month, said that few pundits predicted Trump would win the Republican nomination and few people foresaw the decision by British voters to exit the European Union.

The senator from Virginia also raised the prospect that a billionaire sympathetic to Trump or a “shadowy group” could pour millions into television advertising in the remaining months of the election.

Clinton led Trump among registered voters in North Carolina, 48 percent to 39 percent, in a NBC News/Wall Street Journal/Marist poll released last week.

Clinton has gained traction against Trump in several other key states since the conclusion of the Republican and Democratic conventions, a period where Trump has sparked several controversies and made a series of missteps.

In North Carolina, the Clinton campaign is banking on long-term trends that it sees working in its favor: an influx of college-educated professionals along an urban and suburban corridor that stretches from Raleigh to Charlotte, and an uptick in the African American share of the electorate that is part of the legacy of President Obama’s campaigns.

Obama poured resources into North Carolina in 2008 and eked out a victory over Sen. John McCain (R-Ariz.). He went on to lose by a narrow margin in 2012 to Mitt Romney. Prior to Obama’s 2008 victory, the last Democrat to carry the state in a presidential election was Jimmy Carter, in 1976.

Kaine appeared Monday in the only North Carolina county in the western third of the state that voted for Obama over Romney. Kaine was introduced here by his wife, Anne Holton, until recently the secretary of education in Virginia.

On Tuesday, Kaine plans to visit Fayetteville, which is  home to Fort Bragg, a major U.S. Army installation.

While here in Asheville, Kaine noted that he has won eight elections in his political career and never lost. He said he does it by always running like he’s the underdog -- something he said his ticket should do between now and November.

“We are the underdogs until they call us the winner,” Kaine said.

Following his rally, Kaine made an unannounced stop at Buxton Hall, a popular barbecue restaurant in the city.