CLEVELAND — Hillary Clinton and Donald J. Trump ran virtually parallel campaigns on Monday as they geared up for the final stretch of the presidential race. She made nice with the news media by opening up her campaign plane and chatting with reporters. He followed suit, inviting a smaller group of reporters onto his plane and answering questions during the 30-minute flight.
She took along her running mate, and so did he, as both focused on Ohio and nearly crossed paths in Cleveland. Their motorcades all but passed each other, and all four candidates’ planes ended up on the tarmac at Cleveland Hopkins International Airport at the same time.
Mrs. Clinton moved on several fronts on Monday to confront nagging doubts about her candidacy, despite her comfortable lead in many swing-state polls. Courting labor supporters, she met with union leaders in Cleveland while her husband, Bill Clinton, appeared at a Labor Day parade in Detroit. Seeking the backing of progressive voters, she enlisted her primary opponent, Senator Bernie Sanders of Vermont, who made his first solo appearance on Mrs. Clinton’s behalf at a rally in New Hampshire.
And her outreach to reporters included her most extensive question-and-answer session with them in months. She expressed alarm “about the credible reports about Russian government interference in our elections” through hacking, saying, “We’ve never had a foreign adversarial power be already involved in our electoral process.”
Not to be outdone, Mr. Trump used his airborne meeting with reporters to clarify his views on immigration, saying he opposed any path to citizenship for the 11 million immigrants in the country illegally. But he did not explicitly rule out a long-term path to legal status if the nation’s immigration system is overhauled.
“We’re going to make that decision into the future,” Mr. Trump said. But, he added, “to become a citizen, you are going to have to go out and come back in through the process. You’re going to have to go out and get in line. This isn’t touchback. You have to get in line.”
On the plane, Mr. Trump also told reporters that, “as of this moment,” he planned to attend all three debates, and that only a “natural disaster” could make him change his mind. He added that, while he was preparing, he was not holding mock debate sessions.
Labor Day is traditionally the beginning of a two-month sprint to Election Day, in which candidates try to seize voters’ attention as summer fades and debates loom. Monday was no exception. The visits to Ohio by Mr. Trump and Mrs. Clinton — along with their respective running mates, Gov. Mike Pence of Indiana and Senator Tim Kaine of Virginia — highlighted the importance of a state that Republicans believe Mr. Trump must win to have any shot of reaching the White House.
“Labor Day comes, and it’s kind of like a recalibration,” said Beth Myers, who managed Mitt Romney’s 2008 presidential campaign and served as his senior adviser in 2012. “You see the finish line, you see that there’s not too many game-changing events left, and most campaigns take a measure of where you are on Labor Day.”
This cycle, however, both candidates have eschewed traditional campaigning, albeit in divergent ways. Normally, they would already have been circling each other in swing states.
But Mrs. Clinton has spent most of the summer away from the campaign trail, focusing on fund-raising in places like the Hamptons and Beverly Hills with celebrities like Jimmy Buffett and Harvey Weinstein. Mr. Trump has also kept a languid pace, favoring large rallies, often in the evening, over several daily stops.
Mr. Trump, a political novice, and Mrs. Clinton, a veteran politician, are confronting historically low approval ratings among voters for whom they are well-known commodities.
“Labor Day used to be this big, important marker in the campaign season,” said Amy Walter, the national editor at the nonpartisan Cook Political Report. “A kickoff, if you will. Today, it feels like the start of the third quarter instead of the kickoff.”
“The candidates are well-defined, the ads have been running for months and TVs have been saturated with talking heads,” she added.
Mr. Trump tried to burnish his image as a statesman last week with a hastily arranged trip to Mexico City. He has also tried to increase his outreach to minorities, from a promised “softening” on immigration that concluded with a fiery, nativist speech in Phoenix, to a stop at a black church in Detroit.
That approach was also on display on Monday. At a diner in Cleveland, Mr. Trump met Maria Hernandez, a Mexican-American who said she was supporting him. “Mexican-American supports Trump,” he said. “It’s so nice.” Then he turned to the nearby reporters to emphasize his focus group of one: “Make a note of it, guys,” he said.
Earlier, speaking to a dozen white men and a lone white woman at an American Legion post here, Mr. Trump criticized China’s treatment of President Obama: When the president landed in Hangzhou for the Group of 20 summit meeting, the host country forced him to disembark from the plane’s belly. Mr. Trump said he would not have gotten off the plane, but instead would have urged his crew to “get out of here.”
Mrs. Clinton’s appearance in Cleveland was meant as a show of labor support during a campaign in which many rank-and-file union members were drawn to Mr. Sanders’s promise to take on income inequality. At a Labor Day festival here, she and Mr. Kaine were joined by the A.F.L.-C.I.O.’s president, Richard L. Trumka; Lee Saunders, the president of the American Federation of State, County and Municipal Employees; and Randi Weingarten, the president of the American Federation of Teachers, one of the first unions to endorse Mrs. Clinton.
Mrs. Clinton’s surrogates were also out in force. In Pittsburgh, Mr. Kaine and the man he hopes to succeed, Vice President Joseph R. Biden Jr., spoke at a rally before the city’s Labor Day parade. Mr. Kaine assailed Mr. Trump for refusing to release his tax returns, then turned the stage over to Mr. Biden.
“My name is Joe Biden, and I work for Hillary Clinton and whatever the hell this guy’s name is,” he said.
Mr. Sanders, at a rally in Lebanon, N.H., praised Mrs. Clinton for supporting a host of progressive positions.
“I would hope and ask you all, very much, that we have got to do everything we can to make sure that Hillary Clinton is elected president,” he said. “But two days after the election, we have got to continue the pressure.”
Addressing an issue that has dogged the campaign, Mr. Clinton defended the Clinton Foundation. And he criticized Mr. Trump over his own foundation, referring to a Washington Post report that found that his charitable organization paid the Internal Revenue Service a $2,500 penalty this year after improperly giving a political contribution to a campaign group with ties to the attorney general of Florida, Pam Bondi.
Mr. Trump discussed the issue in his talk with reporters aboard his plane. He denied any impropriety on either his part or Ms. Bondi’s concerning the $25,000 donation.
At the time of the donation in 2013, Ms. Bondi was considering whether to investigate Trump University for fraud. In the end, she did not do so.
“I never spoke to her, first of all, she’s a fine person beyond reproach,” he said when asked about the controversy. “I never even spoke to her about it at all. She’s a fine person. Never spoken to her about it. Never.”
Many attorneys general besides Ms. Bondi, he said, decided against pursuing any action regarding Trump University. “I’ll win that case in court,” he said. “Many turned that down.”
“I never spoke to her,” he added, again referring to Ms. Bondi.
When asked what he expected to get out of the donation, he would only say: “I’ve just known Pam Bondi for years. I have a lot of respect for her. Never spoke to her about that at all. I just have a lot of respect for her, and she’s very popular.”
Amy Chozick contributed reporting from Cleveland, Thomas Kaplan from Pittsburgh, and Yamiche Alcindor from Lebanon, N.H.