Republican Donald Trump waved his finger at Hillary Clinton and denounced her for supporting her husband's trade deals while he was president. But his occasional sniffling was what stood out in the early minutes of the presidential debate Monday night as he faced off against Clinton in New York. 

His sniffling comes days after Clinton appeared to get sick at a Sept. 11, 2001 anniversary event, prompting Trump to accuse her of being too ill to serve in the White House. Both candidates are older than recent presidential hopefuls. Clinton, 69, and Trump, 70,  would be the oldest ever sworn into office.

Trump is known for his impolite rhetoric on the campaign trail that can occasionally come off like a reality TV star looking for extra air time rather than a candidate hoping to lead the U.S. He alluded to his penis size during a GOP debate, belittled his Republican rivals' height, weight and spouses, and, more recently, Trump shocked pundits over the weekend when he said on Twitter he would invite Gennifer Flowers, a former model who had a sexual affair with Bill Clinton, to attend the debate. His campaign manager, Kellyanne Conway told CNN’s "State of the Union" that her candidate was trying "to get into the head of Hillary Clinton."

Many voters seem enamored with Trump's straightforward approach and outsider status. Clinton had 46 percent support nationally compared with 44 percent for Trump in a Washington Post poll released over the weekend. Libertarian Party nominee Gary Johnson with 5 percent and Green Party nominee Jill Stein at 1 percent were not invited to the debate because of their low support.

More than 100 million Americans were expected to watch the debate at Hofstra University in Hempstead, New York. The topics were America's direction, achieving prosperity and securing America.