Which candidates are bumping elbows on Labor Day?

Adam Gabbatt of The Guardian newspaper holds images of possible Republican candidates during the Conservative Political Action Conference (CPAC) in National Harbor, Md., Thursday, Feb. 26, 2015. AP Photo/Carolyn Kaster

For many Americans, Labor Day is just the end of summer, linen clothing, white shoes and slower work schedules. Few may remember the Labor Day's political origins - Grover Cleveland declared the holiday to celebrate the working man in order to curry favor with the labor movement (he lost the Democratic nomination anyway) - and now it has come to mark the unofficial quadrennial kickoff of the presidential campaign season.

On Monday, the 2016 Republican and Democratic presidential hopefuls will fan out across Iowa and New Hampshire to walk in parades, eat barbecue, shake hands and take selfies with voters. And given the large field of candidates, there will be many who are eating barbecue with and taking selfies with the same voters in the same towns and parades. Here's a look at who has to compete for attention and who has the town to themselves this Labor Day.

Hillary Clinton and Martin O’Malley: Almost stepping on each other’s toes

Former Secretary of State Hillary Clinton (L); former Maryland Gov. Martin O'Malley (R) Getty Images

Democratic frontrunner Hillary Clinton and former Maryland Gov. Martin O'Malley have Iowa to themselves Monday. They are both traversing the eastern half of the state, but O'Malley will stick to the northern half while Clinton stakes out the south.

Clinton attends the Annual Hawkeye Labor Council AFL-CIO Labor Day Picnic in Cedar Rapids, Iowa, followed by the Quad City Federation of Labor's Salute to Labor Chicken Fry in nearby Hampton, Illinois, and will round out the day at the Des Moines-Henry County Labor Council Picnic in Burlington, Iowa.

She has no parades on her schedule this holiday, a departure from July fourth, when she marched in a parade and the headlines were all about her campaign corralling the press with a rope.

O'Malley swings by the Jackson County Labor Day Meet and Greet in Maquoketa, Iowa, before heading to the Dubuque, Iowa Labor Council Labor Day Picnic and Iowa City, Iowa Federation of Labor Picnic.

The former governor has spent the last several weeks arguing vigorously that the Democratic candidates need more opportunities to debate - and has gone so far to suggest that the Democratic Party rigged the debate schedule in Clinton's favor. He also told reporters that the party was "going to be defined and branded by questions like what did Secretary Clinton know" - a reference to the questions about her private email server - if Democrats don't start debating sooner than October.

Democratic presidential hopeful Sen. Hillary Rodham Clinton, D-N.Y., left, speaks during the Woodbury County Labor Day Picnic in Sioux City, Iowa, Monday, Sept. 3, 2007. AP Photo/Charlie Neibergall

Clinton spent her last Labor Day on the campaign trail in Iowa as well, though she was in Sioux City on the western side of the state at a barbeque for the Northwest Iowa Labor Council and the Woodbury County Democratic Party. That day she was at the same event as former New Mexico Gov. Bill Richardson, former North Carolina Sen. John Edwards, and then-Delaware Sen. Joe Biden.

Biden, who is considering whether to challenge Clinton once again for the Democratic nomination, is spending Labor Day in Pittsburgh, Pennsylvania. He'll have the company of AFL-CIO President Richard Trumka, a powerful figure in Democratic politics.

Bernie Sanders and Lincoln Chafee: Breakfast in New Hampshire

Vermont Sen. Bernie Sanders (L); former Rhode Island Gov. Lincoln Chafee (R). Reuters / AP

Bernie Sanders, an Independent senator from Iowa, couldn't have a more different campaign from former Rhode Island governor and senator (and former Republican) Lincoln Chafee.

While Sanders keeps drawing record-breaking crowds for his events, Chafee sometimes can't get anyone to tell a pollster they're voting for him. But they'll be on equal turf at the New Hampshire AFL-CIO Labor Day Breakfast in Manchester, New Hampshire.

Later in the day, they'll attend a second event at the Amherst, New Hampshire Democrats Labor Day Barbeque. Sanders will go on to be the lone Democratic representative at the Milford, New Hampshire Labor Day Parade.

Lindsey Graham, Carly Fiorina, John Kasich and Scott Walker: Can’t get any alone time with New Hampshire voters

Republican presidential candidates gather on stage before a forum Monday, Aug. 3, 2015, in Manchester, N.H. From left: Jeb Bush, Ben Carson, Chris Christie, Carly Fiorina, Lindsey Graham, Bobby Jindal, John Kasich, George Pataki, Rick Perry, Rick Santorum, and Scott Walker. AP Photo/Bill Sikes

New Hampshire is a small state, but with a 17-person Republican field, there just aren't enough places to go for each candidate to get his or her own Labor Day time with voters.

At noon, South Carolina Sen. Lindsey Graham, former Hewlett-Packard CEO Carly Fiorina and Ohio Gov. John Kasich will march in the Milford, New Hampshire Labor Day Parade (along with Sanders, who will be the lone Democrat there). The three Republicans could feasibly carpool, since at 3 p.m. they'll meet again at the Salem, New Hampshire GOP Labor Day Picnic. There they'll be joined by yet another Republican candidate, Wisconsin Gov. Scott Walker.

The picnic is part of a busy day for Walker: He has six stops planned throughout the day for his motorcycle tour of New Hampshire.

Fiorina and Kasich also have additional events planned that should get them some time with voters when they don't have to compete with their fellow candidates.

Marco Rubio and Rick Santorum: Solo in South Carolina

Sen. Marco Rubio, R-Florida (L); Former Pennsylvania Sen. Rick Santorum (R).

Candidates tend to spend a little time in South Carolina, which is the third state in the nominating process for both Democrats and Republicans. But only Florida Sen. Marco Rubio and former Pennsylvania Sen. Marco Rubio will abandon the early states of Iowa and New Hampshire to spend Labor Day there.

Rubio has a town hall scheduled with Rep. Trey Gowdy, R-South Carolina, and Sen. Tim Scott, R-South Carolina in North Charleston. Santorum will participate in the Chapin, South Carolina Labor Day Parade.

Santorum also participated in Chapin's Labor Day parade in 2011 when he was shut out of the American Principles Project Palmetto Freedom Forum Debate because he didn't have at least 5 percent support in the polls. The debate isn't happening this year, but he would have faced the same problem since he usually gets just one or two percent support in polls of the 2016 Republican candidates. He kept a busier schedule in 2012, though, also going to a Labor Day festival in Simpsonville, South Carolina and an evening campaign rally in Greenville, South Carolina.

Republican presidential candidates, from left, Rep. Michele Bachmann, R-Minn., businessman Herman Cain, former Rep. Newt Gingrich, Rep. Ron Paul, R-Texas, and former Massachusetts Gov. Mitt Romney pose before the American Principles Project Palmetto Freedom Forum Monday, Sept. 5, 2011, in Columbia, South Carolina. AP Photo/ Mary Ann ChastainAP

The Palmetto Freedom Forum Debate meant South Carolina got most of the Labor Day campaign action in 2012. The event drew former Rep. Michele Bachmann, businessman Herman Cain, former House Speaker Newt Gingrich, former Rep. Ron Paul, and 2012 GOP nominee Mitt Romney. Then-Gov. Rick Perry of Texas was also supposed to attend, but canceled at the last minute because of wildfires that were raging in Texas.

Perry, whose 2016 campaign is on life support, hasn't announced whether he has plans to campaign on Labor Day.