Donald Trump is campaigning Tuesday in the western state of Arizona, while Hillary Clinton rallies supporters in Pennsylvania, but the focus will be in Virginia where their running mates are holding the only vice presidential debate before the November 8 election.
The matchup between Republican Mike Pence and Democrat Tim Kaine comes days before Trump and Clinton will square off in their second debate.
On Monday, the two presidential candidates continued criticizing each other, with Clinton attacking Trump's tax returns and Trump keying on Clinton's use of a private email system while she was secretary of state.
Clinton said at an event in the important midwestern state of Ohio that Trump is "the poster boy for the same rigged system that he would make even worse."
She leveled the new allegations in the aftermath of a recent New York Times report showing a portion of the Republican nominee’s 1995 state tax returns in which he declared $916 million in business losses from failing casinos and other ventures. It was a deduction so large that it could have allowed the real estate mogul to legally avoid paying U.S. income taxes for up to 18 years.
"What kind of genius loses a billion dollars in a single year?" Clinton asked.
The Trump campaign has not denied the accuracy of the returns, with the real estate mogul saying on his Twitter account, "I know our complex tax laws better than anyone who has ever run for president and am the only one who can fix them."
He added Monday at an event in the western state of Colorado that he is a "big beneficiary" of the tax system, but that he wants to "make it fair for everybody."
Trump has defied four decades of U.S. presidential campaign tradition by refusing to release his tax returns. He says his U.S. income tax returns for recent years are under audit by federal officials and that he will release them when the reviews are finished, even though there is no prohibition against disclosing the information ahead of that time.
Regarding Clinton's emails, Trump said a closed Federal Bureau of Investigation probe was "rigged" and was bigger than the Watergate scandal that led former U.S. President Richard Nixon to resign in the 1970s.
Investigators concluded that Clinton was "extremely careless" in her use of the emails system but that no criminal charges were warranted.
Trump also drew the ire of veterans' groups after he suggested that soldiers who suffer from mental health issues might not be as strong as those who don't.
"When people come back from war and combat and they see things that maybe a lot of the folks in this room have seen many times over, and you're strong and you can handle it, but a lot of people can't handle it," Trump said.
The comment drew swift condemnation from critics as well as veterans' groups that have been working for years to reduce the stigma associated with mental health issues in an effort to encourage soldiers to seek treatment.
