Donald Trump and Hillary Clinton have entered the final, two-month stretch of the US presidential campaign in the battleground state of Ohio as the Republican nominee saw a strengthening in opinion poll numbers that put pressure on his heavily favoured Democratic rival.
Monday's Labor Day holiday is the traditional kickoff to the frenzied, last stretch of campaigning ahead of the November 8 election, and both Trump and Clinton chose to begin their day in Cleveland.
Trump, along with his vice presidential nominee, Indiana Governor Mike Pence, attended a Cleveland area meeting with labour leaders and union members before heading to a state fair in the Youngstown area.
Clinton, scheduled to make a stop at a local business before marching in a Labor Day parade, told the press corps - travelling on the same plane with her for the first time - that it was the "last moment before the mad dash" to the White House.
"I'm ready, I'm more than ready," Clinton said before takeoff.
While Trump still trails Clinton in many battleground states where the election will likely be decided, he has drawn close to even with her in some national polls and even inched ahead of the Democrat in others.
The most recent Reuters/Ipsos poll on Friday showed Trump had the support of 40 per cent of likely voters to 39 per cent for Clinton, erasing her recent eight-point lead.
Trump's rebound from a series of self-inflicted wounds has followed the hiring of a new campaign management team, and the Republican nominee is showing more discipline on the stump, reading his rally speeches from teleprompters.
Trump has been helped by what his campaign saw as a positive week last week in which he made a quick trip to Mexico, appearing side by side with Mexican President Enrique Pena Nieto , and visited a black church in Detroit.
An immigration speech Trump gave following his trip to Mexico, however, drew criticism from some of his Hispanic supporters and several backers advising him on the issue decided to part ways with his campaign.
Trump told the labour meeting his rising poll numbers are a sign his messages about tossing bad international trade deals and curbing illegal immigration are resonating with voters.
Clinton, who was President Barack Obama's first-term secretary of state, appeared at few public campaign events during the latter half of August, instead raising funds at high-dollar events in the East Coast vacation spots of Martha's Vineyard and the Hamptons, and with celebrities in Los Angeles and high-tech leaders in Silicon Valley.
Clinton's campaign announced that it had raised $US143 million ($A188 million) in August for her presidential bid and the Democratic Party.
Clinton is again on the defensive over her use of a private email server and possible conflicts of interest with her family foundation while she was secretary of state, which have caused unease for some voters. But experts still see the Democratic nominee as the odds-on favorite to win the presidency.
Some Democratic strategists criticised the news media over the weekend for not giving more coverage to a controversy involving Trump's charitable foundation.
The Washington Post said the New York businessman paid the Internal Revenue Service a $US2,500 penalty this year after it was revealed that his foundation had violated tax laws by giving a political contribution to a campaign group connected to Florida's attorney general, Pam Bondi, who has endorsed Trump.
"With anyone other than Trump, this would be a major story and it's a massive failure from the media that it isn't," tweeted Dan Pfeiffer, a former senior White House adviser to Obama.
