Sen. Bernie Sanders, Michael Avenatti, Sen. Cory Booker and Michael Bloomberg are among those visiting early-primary states. (AP/Reuters)

DURHAM, N.H. – The unofficial start of the 2020 presidential campaign will come the moment next week’s midterms are called. But a number of potential Democratic contenders are not so keen to wait.

In a pre-season rush, early-primary states already have seen an explosion of visits by Democrats eager for a shot to take on President Trump in 2020. Most are coy about their plans and fall into the not-ruling-it-out category – while vowing they’re strictly focused for now on the midterms.

“I’m really so obsessed and focused on the midterms,” Sen. Cory Booker, D-N.J., said Sunday during a jam-packed swing through New Hampshire, the state that traditionally holds the first primary in the race for the White House. “I’m literally putting thousands of miles on the road, so I’m not even focusing on that.”

He said he plans to schedule a day of rest after Nov. 6, “and then start thinking about 2020.”

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It’s debatable whether Booker, widely seen as a White House contender, truly is not giving a thought to running for president. What isn’t debatable is that he’s not alone.

The potential presidential contenders are crisscrossing the country as they help Democrats running in November’s elections. And many of them are conveniently parachuting into New Hampshire, as well Iowa, South Carolina and Nevada, the other early-voting states in the primary and caucus calendar. Those visits are sparking more speculation about their 2020 ambitions.

In New Hampshire, the dance floor’s getting crowded.

Over the past two weeks, all these figures have stopped by the Granite State to stump for fellow Democrats on the ballot next week: Booker, Sens. Kirsten Gillibrand of New York and Jeff Merkley of Oregon, former New York City mayor and billionaire media owner and gun safety advocate Michael Bloomberg, former Housing and Urban Development secretary and former San Antonio mayor Julian Castro, former Virginia governor Terry McAuliffe, Ohio Rep. Tim Ryan, and high-profile and controversial attorney Michael Avenatti.

Sen. Bernie Sanders of Vermont, who crushed Hillary Clinton in the 2016 Democratic primary in New Hampshire but lost the nomination, returns on the Sunday before the midterms.

Iowa, which kicks off the primary and caucus calendar, also has hosted a slew of potential 2020 contenders. Over the past two weeks, Sanders; Merkley; Castro; Sens. Kamala Harris of California and Amy Klobuchar of Minnesota; Govs. Jay Inslee of Washington state, Steve Bullock of Montana and John Hickenlooper of Colorado; Rep. Tulsi Gabbard of Hawaii; 2016 Democratic presidential candidate and former Maryland Gov. Martin O’Malley; and Rep. John Delaney of Maryland, who’s already declared his 2020 candidacy, all have stopped in the first caucus state.

Former Vice President Joe Biden jumps onto the Iowa campaign trail on Tuesday.

South Carolina and Nevada, too, are seeing a good bit of 2020 traffic.

Some of the potential White House hopefuls are quite open about their possible 2020 intentions.

Castro told Fox News last week that “I’m likely to announce after the first of the year if I decide to run.”

Others are less transparent.

Gillibrand avoided answering any questions about her possible presidential ambitions during a quick stop in New Hampshire to help the Democratic gubernatorial nominee.

“I’m here because I want Molly Kelly to be the next governor of New Hampshire,” she told reporters.

Asked if she had any timetable to decide on a White House run, Gillibrand answered, “I’m focused on my own Senate race.”

Publicly, Gillibrand has been downplaying talk of a bid – at a debate last week, she said she would serve out her full Senate term, though her opponent said he doesn’t believe it.

For those who ultimately take the presidential plunge, these early pre-season stops can pay dividends. Potential presidential contenders make friendships that could help down the road and those without much name recognition outside their home states can build up their national profile.

But there are also other reasons for the visits.

“This is an audition of sorts for the political operatives across the Granite State,” New England College political science professor Wayne Lesperance explained. “These would-be candidates want to get the attention of top-tier operatives here and can only do so if they are present and appear to be serious about running.”

While the visits are a win-win for the possible presidential contenders, it’s debatable how much their campaign stops will impact the 2018 midterms.

“It’s not entirely clear if their presence makes much of a difference to 2018 candidates this close to Election Day,” Lesperance said.