Iowa gets most of the early presidential buzz, but the 2020 presidential campaigns have come tumbling into Minnesota earlier than ever, a sign of the state's new status as a battleground in the making.

Less than a month after President Donald Trump vowed to carry the state at a Target Center rally in Minneapolis, Vermont Sen. Bernie Sanders is expected to fill up Williams Arena on Sunday night. In August, Massachusetts Sen. Elizabeth Warren packed a town hall meeting at Macalester College.

It's been decades since the state got this kind of attention a year ahead of a presidential election, and not only because of a crowded field of Democratic challengers that includes Minnesota Sen. Amy Klobuchar.

As the Democrats battle to hold a state that hasn't gone to a Republican presidential contender since 1972, they will also be looking for momentum in a frenetic primary season. It comes to a head on March 3, when voters in Minnesota and 15 other states and territories go to the polls in the traditional "Super Tuesday" showdown.

Minnesota's primary on Super Tuesday — exactly a month after the first-in-the-nation Iowa caucuses — ends a caucus system frequently dominated by insiders and party activists, often with limited attention from national campaigns.

Sanders, looking to stage a repeat of his 2016 win in Minnesota's presidential caucus, is once again courting the party's liberal base in the primary. He'll be joined Sunday by U.S. Rep. Ilhan Omar of Minneapolis, who endorsed him in October.

Both Sanders and Warren, his rival on the left side of the Democratic field, now have paid campaign staff in Minnesota working to mobilize volunteers and build get-out-the-vote operations. South Bend, Ind., Mayor Pete Buttigieg and former Texas U.S. Rep. Beto O'Rourke (who dropped out of the race Friday) have also turned up in Minnesota. Vice President Joe Biden hasn't yet, nor has he made any Minnesota hires, but his campaign says that's coming. Klobuchar, still a dark horse nationally, faces high expectations and stiff competition in a home state win — if she's still in the race by March 3.

"I think you're going to see a lot of these candidates visiting Minnesota in December and January," said Ken Martin, chairman of the Minnesota Democratic-Farmer-Labor Party.

Thanks to Minnesota's recent early-voting expansion, voters will be able to cast primary ballots beginning on Jan. 17. While the votes won't be counted until after polls close on March 3, it means potentially thousands could vote several weeks before the Iowa caucus and the New Hampshire primary.

For Democrats, the stakes of laying campaign groundwork go beyond March 3. A robust infrastructure and volunteer network could make a difference in winning Minnesota's 10 electoral votes in the November 2020 general election. Trump, who lost the state by a narrow 1.5% margin in 2016, is hiring staff and pledging to spend $30 million.

"In these states, this early organizing, the volunteer force just becomes critical," said Jennifer Koch Donovan, a Democratic strategist who served as Obama's Minnesota caucus director in 2008. "If I was a presidential candidate, I would show up to Minnesota as early as I can."

Besides Klobuchar, whose campaign headquarters are in Minneapolis, Sanders and Warren have been the most active Democrats in Minnesota. Both campaigned in the state in August, and Warren won an unscientific "bean ballot" straw poll at the DFL's State Fair booth — besting Klobuchar. Biden has been less visible, but a spokesman said the campaign would ramp up ahead of Super Tuesday.

So far, Biden's Minnesota campaign relies on his near-universal name identification rather than a grassroots operation. He has no paid campaign staffers in the state and no Minnesota headquarters. He has one prominent endorsement, from state Rep. Rena Moran, DFL-St. Paul. A Biden campaign spokesman said the focus is on logging big wins across Super Tuesday states, with recent hires in states like California and Florida and plans to build campaign operations and Minnesota and other states.

Biden was on Trump's mind during his Minneapolis campaign rally last month, when he singled out the former vice president with some of his most biting personal attacks.

A Star Tribune Minnesota poll taken after Trump's rally in Minneapolis found Biden, as well as Warren, currently leads Trump by double digits in the state. Sanders leads by 9 points. Klobuchar, the best known among Minnesota voters, held the widest lead at 55% to 38%.

Klobuchar's campaign has an organizing director working on the Minnesota primary. She has also nailed down endorsements from most of the state's prominent Democrats, with Sanders supporters Omar and Attorney General Keith Ellison the big exceptions. Other contenders like Sens. Kamala Harris of California and Cory Booker of New Jersey have yet to lavish much attention on Minnesota.

Activists outside the official campaigns are engaging early, too. Members of the Twin Cities chapter of the Democratic Socialists of America, which endorsed Sanders, are spending weekends talking to voters about their candidate and his marquee issues, like Medicare for All.

Sanders beat Hillary Clinton by nearly 20 points in Minnesota's 2016 caucus. The participatory aspect of a caucus has been a strength for his grassroots style of politics, but analysts say it's difficult to predict how well that will translate to what's likely to be a higher-turnout primary.

Tim Schaefer, co-chair of Twin Cities DSA, is confident in Sanders' ability to repeat his 2016 win.

"Sanders is uniquely positioned as someone who is able and has demonstrated his ability to activate new voters and broaden the base that Democratic candidates traditionally enjoy," he said.

Warren's campaign, taking a similar organizing approach, recently hired Emily Jensen as its Minnesota state director. She was Minnesota caucus director for the Sanders campaign in 2016.

"We will compete and organize everywhere," said Alexis Krieg, a spokeswoman for Warren's campaign. "We're laying the groundwork to have a huge movement of grassroots supporters that will own a piece of the campaign and be in the fight with us."

Buttigieg, who held Twin Cities fundraisers in April, has a smaller footprint in Minnesota, though his campaign has a regional organizing director based in the Twin Cities. Grassroots volunteers are hosting meetups — dubbed "Pete-ups" — in homes and at coffee shops and debate watch parties. Unlike the Sanders and Warren fans, Buttigieg backers say making inroads can be a challenge.

"I can see people looking at the signs and mouthing to themselves, 'Who's Pete?' " said Minnesotans for Pete volunteer Gloria Everson, who helps organize "Honk and Wave for Pete" outings to boost awareness. "They don't know him yet."

But, like her rival organizers, Everson says she's playing the long game.