Democrats with an eye on challenging President Trump Donald John TrumpUS reimposes UN sanctions on Iran amid increasing tensions Jeff Flake: Republicans 'should hold the same position' on SCOTUS vacancy as 2016 Trump supporters chant 'Fill that seat' at North Carolina rally MORE in 2020 are already making travel plans that could position themselves for a potential bid.

Progressive favorite Sen. Bernie Sanders Bernie SandersNYT editorial board remembers Ginsburg: She 'will forever have two legacies' Two GOP governors urge Republicans to hold off on Supreme Court nominee Sanders knocks McConnell: He's going against Ginsburg's 'dying wishes' MORE (I-Vt.) sparked the latest round of intrigue last week when he announced he’d be heading back to Iowa, which hosts the first vote of the presidential primary race, to campaign for a former staffer’s congressional bid.

Here’s a rundown of which potential 2020 contenders have already made the pilgrimage to key early primary states Iowa or New Hampshire, sorted by those who have traveled to these states the most.

Former Missouri Secretary of State Jason Kander: 10 trips to Iowa, 7 trips to New Hampshire

Kander, a former Missouri secretary of State who ran a surprisingly strong Senate race in 2016, appears to have an affinity for the Hawkeye and Granite states. He’s averaged more than one trip a month since 2016 to one of the early primary states.

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He’s lent a hand to a handful of local candidates in both states, leading fundraisers and holding events. He’s also attended local Democratic fundraisers and academic events, according to the Iowa Starting Line blog, which tracks candidate visits to the key state.

Kander, 36, is also building his profile in the party with a political organization meant to fight voter suppression.

Maryland Rep. John Delaney John DelaneyCoronavirus Report: The Hill's Steve Clemons interviews Rep. Rodney Davis Eurasia Group founder Ian Bremmer says Trump right on China but wrong on WHO; CDC issues new guidance for large gatherings The Hill's Coronavirus Report: Kansas City Mayor Quinton Lucas says country needs to rethink what 'policing' means; US cases surpass 2 million with no end to pandemic in sight MORE: 7 trips to Iowa, 5 trips to New Hampshire

As the only major candidate who has already declared a presidential bid, Delaney has had a very active travel schedule.

He’s returning to Iowa over Presidents Day weekend for his seventh swing through Iowa, where he’s launched a monthlong $1 million ad buy meant to introduce himself to voters and highlight a bipartisan streak.

And he’s a frequent visitor to New Hampshire, where the 54-year-old lawmaker held a slew of campaign-style events meant to introduce himself to local leaders and voters.

Former Maryland Gov. Martin O’Malley: 5 trips to Iowa, 3 trips to New Hampshire

O’Malley may have ended his 2016 presidential campaign after barely registering on the scoreboard in the Iowa caucuses, but his travel schedule makes him look like a man who still has his eye on the White House.

O’Malley’s leadership PAC commissioned a poll of his standing in Iowa last year and the former governor has been one of the more active Democratic surrogates for local candidates in both Iowa and New Hampshire.

After an initial stop in New Hampshire in April for a few campaign-style events, O’Malley, 55, returned to the state twice more in 2017 to campaign for local Democratic candidates. He also traveled to Iowa five times, according to Iowa Starting Line, where he campaigned for four local candidates and spoke at a variety of events.

Sanders: 3 trips to Iowa, 2 trips to New Hampshire

The senator has a busy schedule for his latest Iowa trip, campaigning for his former aide and headlining a rally in Cedar Rapids against the GOP’s recent tax plan.

Sanders’s trip to Iowa will be his third since the election. The 76-year-old senator stopped by Des Moines once in July for an Iowa Citizens for Community Improvement event and returned to the state a month later for a swing through Iowa City while promoting his book “Bernie Sanders Guide to Political Revolution.”

He’s also been to New Hampshire twice — once just weeks after the election to promote another book, and again last September for an American Federation of Labor and Congress of Industrial Organizations Labor Day breakfast.

Ohio Rep. Tim Ryan Timothy (Tim) RyanMourners gather outside Supreme Court after passing of Ruth Bader Ginsburg Lincoln Project hits Trump for criticizing Goodyear, 'an American company' Biden defends Goodyear after Trump urges boycott MORE: 2 trips to Iowa, 3 trips to New Hampshire

Ryan made noise in the House last year when he launched a failed bid to oust House Minority Leader Nancy Pelosi Nancy PelosiSunday shows preview: Justice Ginsburg dies, sparking partisan battle over vacancy before election Trump is betting big on the suburbs, but his strategy is failing 'bigly' Trump orders flags at half-staff to honor 'trailblazer' Ginsburg MORE (D-Calif.). While he wasn’t successful, he’s raised his profile by calling for Democrats to make stronger inroads to the working class.

Ryan, 44, delivered a graduation speech at Iowa’s Maharishi University graduation last June, and returned to the state for the Polk County Democrats’ Steak Fry with Rep. Seth Moulton Seth MoultonThe Hill's Morning Report - Presented by Facebook - Markey defeats Kennedy; Trump lauds America's enforcers in Wisconsin Moulton fends off primary challenges in Massachusetts Portland: The Pentagon should step up or pipe down MORE (D-Mass.). He’s also visited New Hampshire on three occasions, according to New Hampshire television station WMUR.

Minnesota Sen. Amy Klobuchar Amy KlobucharThe Hill's Morning Report - Sponsored by The Air Line Pilots Association - White House moves closer to Pelosi on virus relief bill EPA delivers win for ethanol industry angered by waivers to refiners It's time for newspapers to stop endorsing presidential candidates MORE: 2 trips to Iowa

The Minnesota senator may not have the national name recognition of some of the top Democratic presidential hopefuls, but she’s also started visiting Iowa.

Klobuchar, 57, spoke to the Linn County Phoenix Club in Marion in May, and attended a fundraiser for the Polk County Democrats. A few months later, she returned to the crucial early state for a speech at Iowa State University.

Former Vice President Joe Biden Joe BidenMomentum growing among Republicans for Supreme Court vote before Election Day Trump expects to nominate woman to replace Ginsburg next week Video of Lindsey Graham arguing against nominating a Supreme Court justice in an election year goes viral MORE: 1 trip to New Hampshire

After keeping a low profile in the early months of the Trump administration, Biden, 75, is kicking up his political activity. He spoke at an annual dinner hosted by the New Hampshire Democratic Party in April, and plans to be a frequent campaigner for Democrats in the midterms.

Former Secretary of State John Kerry John Forbes KerryThe Memo: Warning signs flash for Trump on debates Divided country, divided church TV ads favored Biden 2-1 in past month MORE: 1 trip to Iowa

Kerry, who represented Massachusetts in the Senate before becoming secretary of State during the Obama administration, won both the Iowa caucus and the New Hampshire primary during his 2004 presidential bid.

And while Kerry will be almost 77 years old on Election Day of 2020, he’s still seen as a possible Democratic candidate.

Kerry traveled to Iowa last December to campaign for Attorney General Tom Miller. While there, he slammed Trump for retweeting anti-Muslim hoax videos.

South Bend, Ind., Mayor Pete Buttigieg: 1 trip to Iowa

Buttigieg, 36, rose to prominence in the months after the election as he waged a surprise campaign to lead the Democratic National Committee.

Part of the younger tier of Democratic leaders, the openly gay mayor has spoken at a variety of Democratic events, including one trip to Iowa for the Progress Iowa Corn Feed.

New York Mayor Bill de Blasio: 1 trip to Iowa

De Blasio is one of the handful of New Yorkers who appears to be considering a bid against Trump in 2020. De Blasio, 56, traveled to Iowa in December to speak at a dinner for Progress Iowa, a progressive group in the state.

Oregon Sen. Jeff Merkley Jeffrey (Jeff) Alan MerkleyThe Hill's Morning Report - Sponsored by The Air Line Pilots Association - Trump, Biden renew push for Latino support Sunday shows - Trump team defends coronavirus response Oregon senator says Trump's blame on 'forest management' for wildfires is 'just a big and devastating lie' MORE: 1 trip to Iowa

Merkley, the only senator to back Sanders’s presidential bid in 2016, has carved out a niche for himself in the Senate as the top Democrat on the Environment and Public Works Committee.

Merkley, 61, took one trip to the Hawkeye State in September, joining Buttigieg at the Progress Iowa Corn Feed.

Moulton: 1 trip to Iowa

Moulton, 39, who joined Ryan at the Steak Fry, is another new face on the national Democratic scene who has also called for new leadership in the party.

He’s spent the 2018 cycle endorsing fellow military veterans mounting bids for Congress, and has raked in serious cash for both his political organization and his endorsed candidates.

Los Angeles Mayor Eric Garcetti: 1 trip to New Hampshire

Garcetti chose not to run for higher office in his own state in 2018, raising speculation he could be interested in a presidential bid.

The 47-year-old mayor of America’s second-largest city dropped by New Hampshire last August to campaign for a candidate in the Manchester mayoral race who ultimately won.