Clinton and Trump are making their closing arguments to American voters, crisscrossing the United States in hopes of winning over last-minute undecided voters and rallying their bases to turn out enthusiastically on Election Day.
Opinion polls show Clinton still holds advantages in states that could be critical in deciding the election.
But her lead has narrowed after a revelation a week ago that the Federal Bureau of Investigation was looking into a new trove of emails as part of its probe into her handling of classified information while she was secretary of state.
A McClatchy-Marist opinion poll released on Saturday of voters nationwide showed Clinton leading by 1 percentage point compared to 6 percentage points in September.
A Reuters/Ipsos tracking poll on Saturday showed Clinton ahead by 4 percentage points nationally compared to 5 points on Friday.
The state opinion polls have found Florida to be one of the most competitive among battleground states - those that are hotly contested because their voters can swing either to Republicans or Democrats.
The 2000 presidential election was decided in Florida after a dispute over votes and recounting of ballots went to the U.S. Supreme Court, which ruled in favor of Republican George W. Bush over Democrat Al Gore.
The Real Clear Politics average of Florida opinion polls found Clinton with a lead of about 1 percentage point - indicating the race there is a virtual tie.
Trump spoke at a rally on Saturday morning in Tampa, Florida, where he continued to criticise Clinton for supporting the Affordable Care Act, also known as Obamacare, in the wake of an announcement that premiums are going to rise next year.
"It's not going to matter because if we win I'm throwing it out anyway," Trump said.
Shortly before Clinton took the stage in Pembroke Pines, Florida, rained poured down.
People in the crowd waiting for Clinton at the outdoor rally remained in place, taking out umbrellas and fashioning garbage bags into head coverings.
"I'm thrilled to be here and boy is this a hardy group, rain or shine you are ready," Clinton said, her voice cracking with hoarseness.
She cut her speech short as she became soaked in rain, saying, "I don't think I need to tell you all of the wrong things about Donald Trump."
At the JFK library in Hialeah, Florida, people lined up outside for early voting. Nearby, supporters of both candidates waved signs and shouted slogans, urging passing drivers to honk their horns.
"We want someone to come in and clean house," said Cuban-American Ariel Martinez, 42, a Trump supporter.
In North Carolina, Trump campaigned along with wife Melania, who has been nearly invisible in the campaign after her speech at the Republican National Convention in July that had passages lifted from a previous speech by Michelle Obama.
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She took a more active role this week with a speech in Pennsylvania.
"It is a movement for all of those who are left behind by a broken and rigged system," Melania Trump said on Saturday of her husband's campaign. "This is a movement which is inspiring and inclusive."
Early voting began in September and the data firm Catalist estimates more than 30 million ballots have been cast in 38 states. There are an estimated 225.8 million eligible U.S. voters. Saturday is the final day for early voting in many Florida counties.
Trump will also campaign Saturday in Nevada and Colorado.
Trump told the crowd in Tampa that there would be a campaign event in Minnesota this weekend, although one had not previously been scheduled. Minnesota has not voted for a Republican since 1984.
His campaign confirmed a rally scheduled for Wisconsin on Sunday has been canceled.
Clinton started the day by stopping by the West Miami Community Center, a Cuban American neighborhood, with telenovela star Jencarlos Canela, a Miami native of Cuban descent.
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She then visited her campaign's office in Little Haiti where there is a large concentration of Haitian-American residents.
Clinton was joined by Sybrina Fulton, the mother of Trayvon Martin, the unarmed black teenager who was shot dead in 2012 by a Sanford, Florida neighborhood watchman, George Zimmerman.
While Trump prefers large-scale rallies, Clinton has filled her campaign schedule with targeted appearances meant to court voters in specific demographics.
Cuban voters have historically favored Republicans, but younger generations have shifted toward Democratic Party candidates.
Celebrities perform for Clinton
Clinton heads to Philadelphia, where she will appear with pop singer Katy Perry for an evening rally.
In what was seen as an effort to defend typically Democratic turf, Clinton on Monday will campaign in Grand Rapids, Michigan, before returning to Pennsylvania for a rally in Philadelphia with President Barack Obama and first lady Michelle Obama, and former President Bill Clinton.
Trump is to make stops on Sunday in Iowa, Minnesota, Michigan, Pennsylvania and Virginia to try to steal away some states that have gone Democratic in recent presidential elections.
Clinton has leaned on her celebrity supporters to draw large crowds in the final days of the campaign.
On Friday night, she appeared in Cleveland with music power couple Jay-Z and Beyonce.
Clinton rallied millennial supporters on a conference call, urging them to vote and get others to do so too.
"I really believe you will decide this election and of course I’m hoping that you will make sure everyone you know will come out and vote because America is counting on us," Clinton said.
Trump has appeared to be struggling with support from his own Republican Party. Last week, Reuters/Ipsos polling found a majority of Republicans thought Clinton was going to win.
This week, however, those numbers flipped and Republicans now narrowly believe he could win.
