The White House contenders clashed from afar - Clinton in battleground Florida and Trump in Pennsylvania - with the sprint to next Tuesday's finish well underway.
For Trump, the day's appearance marked a sharp shift from his standard brash tone as he delivered carefully scripted remarks focused on health care. He cautioned that Clinton's plan to strengthen "Obamacare" would lead to dire consequences, although he offered few specifics about his own plan.
"If we don't repeal and replace Obamacare, we will destroy American health care forever," Trump charged.
He also promised, if elected, to call a special session of Congress to replace the law. Congress would already be in session when the next president takes office, however, raising the question of just what he meant.
Still, frustrated Republicans were encouraged that Trump was focusing on policy prescriptions - for one afternoon, at least - after a roller-coaster campaign marked by self-created controversy and political missteps.
Clinton worked to ensure battleground state voters would not forget Trump's most damaging moments six days before the election.
Alicia Machado, a former beauty queen who Trump previously described as "Miss Piggy," was scheduled to introduce the Democratic nominee in Florida. Trump spent several days in late September assailing the winner of his 1996 Miss Universe pageant, encouraging his Twitter followers this fall to view her "sex tape," although none exists.
The Machado appearance was in line with Clinton's broader closing argument against Trump.
Clinton, as has been all but overlooked in recent months, would be the nation's first female president. Trump has faced allegations of sexual misconduct that complicated his struggle to win over women in both parties.
Clinton unveiled a new television ad Tuesday highlighting Trump's history of sexist statements, including his remark caught in a 2005 video that he kissed women and grabbed their genitals without permission. "Anyone who does what he does is unfit to be president," reads the final scene of the ad, which Clinton's campaign says will run across eight battleground states.
At the same time, both sides sparred over the recent revelation that FBI investigators were again probing Clinton's email practices.
A lawyer for Clinton aide Huma Abedin said Tuesday that her client learned from media reports last Friday that a laptop belonging to her estranged husband, Anthony Weiner, might contain some of her emails. The attorney said Abedin has not been contacted by the FBI about the development but she would cooperate if asked.
The revelation put Democrats on the defensive, at least briefly, and hurt Clinton's plans to promote a positive message over the campaign's final week.
Yet neither Republican nor Democratic operatives view the news as a game-changer in the race for Senate control. The balance of power in Congress could have profound consequences for the future of health care in America, among other policy debates.
Trump on Tuesday promised to replace the federal health care law with health care savings accounts, while allowing states to craft their own Medicaid programs to cover the poor.
The nonpartisan Center for Health and Economy determined this summer that Trump's proposal would make 18 million people uninsured, while also lowering premiums significantly for policies purchased directly by consumers. The nonpartisan Commonwealth Fund predicted that 20 million people would lose coverage under Trump's plan while Clinton's would add coverage for 9 million.
Trump on Tuesday seized on projections of sharp health care cost increases as he campaigned in Pennsylvania, a state where some premiums are expected to rise by more than 40 percent. Trump was introduced by his running mate Mike Pence, who expanded Medicaid coverage as part of Obama's law as Indiana governor.
Pence called Obamacare "a crushing weight" on the American economy. "We're going to pull it off the market so it stops burning up our wallets," he declared.
House Speaker Paul Ryan, who has been silent on Trump's candidacy in recent weeks, told Fox News that electing Clinton and a Democratic-controlled Congress would be "the worst of all possible things."
"For those of us who lived through the 1990s, it's sort of a feeling like deja vu," Ryan said. "This is what life with the Clintons looks like. It's always a scandal, then there's an investigation."
Associated Press writers Lisa Lerer and Erica Werner in Washington and Julie Pace in Dade City contributed to this report.