Donald Trump’s surging presidential bid gets an important test in Minnesota this week, when the billionaire Republican front-runner tries to rack up a win in a state that has not yet had an up-close view of his combative campaign.

The four remaining top contenders from the two parties all have poured months of time and campaign resources into winning Minnesota’s March 1 caucuses. Thousands of party faithful are expected to pack voting sites on Tuesday night with Minnesota’s voting among the dozen caucuses and primaries nationally that make up this year’s pivotal Super Tuesday.

On the Democratic side, both Hillary Clinton and Bernie Sanders have made ­multiple Minnesota stops, amassed impressive volunteer forces and taken to the TV and radio airwaves as they battled to the last minute for support. Sanders has lavished the most personal attention on Minnesota of any candidate from either party, swinging through Hibbing on Friday and Rochester on Saturday evening as he tries to peel off a badly needed win over Clinton in a state his campaign views as friendly turf.

The two main Trump alternatives for Republicans, Sens. Marco Rubio of Florida and Ted Cruz of Texas, also have campaigned in Minnesota and built teams of prominent supporters and volunteers. Trump has never visited, and his campaign made its initial organizing steps here less than a month ago.

But the energy gathering from Trump’s three-state winning streak could materialize at caucus sites in this high-voter turnout state, which has previously shown an unexpected fondness for such unconventional outsider candidates as former Gov. Jesse Ventura.

“Clearly he has momentum within the court of public opinion,” state Republican Party Chairman Keith Downey said of Trump. Downey thinks Trump, Rubio and Cruz all have a shot at winning Minnesota.

With hundreds of delegates at stake on Super Tuesday, this year’s wild, occasionally surreal presidential race is kicking into high gear. While Minnesota’s delegate haul is relatively small, Democratic and GOP candidates alike worked to win here.

“Right now it’s just too tight to tell,” state DFL Party Chair Ken Martin said of Clinton vs. Sanders. In his view, Clinton has assembled a superior get-out-the-vote operation but Sanders has unleashed more “organic energy.” Martin expects good turnout, but doesn’t think it will exceed the 2008 record, when Clinton finished a distant second to Sen. Barack Obama.

If Sanders can win in Minnesota and a handful of other Super Tuesday states, it would make it harder for Clinton to shut down his challenge from the left.

Weekend campaigning

As a crowd awaited Sanders’ appearance at the Mayo Civic Center in Rochester, an organizer for the senator asked how many people signed for a “get out the caucus shift.” Only a smattering of hands went up.

“Not enough hands,” the woman said. “The reality is, it’s awesome you’re here, but if you really love Bernie ... we need you to sign up for these shifts.” She said it wasn’t enough to bring themselves and the person standing next to them out to caucus. “What matters is getting your whole neighborhood out to caucus.”

Besides Sanders’ stumping, Chelsea Clinton was due to campaign here for her mother along with a handful of other high-profile surrogates. Cruz’s father, Rafael, was headlining a couple of Twin Cities events.

Trump’s Minnesota supporters, scrambling to catch up, scheduled a series of weekend events to draw volunteers and to spread strategy about how to caucus for Trump on Tuesday night. A rally on Sunday at a Richfield American Legion hall and a get-together at a Long Lake restaurant on Monday were both in the works.

“I’m a pretty mainstream Republican,” said Sheri Auclair, a party activist from Minnetonka who planned the Richfield rally. “I went to a Trump get-together last week — I walked in there, and I saw all these familiar faces. We all cracked up laughing. We’re part of the silent majority.”

Chris Hupke, a paid organizer for the Trump campaign and a conservative operative from South Dakota, relocated to Minnesota about a month ago after working on his Iowa campaign. That’s the only state Trump has lost so far, and Minnesota’s caucuses, like Iowa’s, reward an organized approach and supporters who know how to work the system.

“I’ve never caucused, I never even knew what a caucus was,” said Corinne Braun of St. Louis Park, who runs a computer consulting business and has helped the Trump campaign spread word of its Minnesota activities on social media. “We’re all just people who were dying to get involved.”

Trump fans in Minnesota interviewed for this story were less likely to cite one issue or another as the basis for their support. Instead, they like his anti-establishment sass, his familiar vow to “make America great again” and his seeming invulnerability to gaffes that have destroyed other candidates.

“This guy can command billions of dollars in free advertising by saying stuff that nobody else in history can say and keep going,” said Don Allen, a Minneapolis blogger and conservative activist who once ran for chairman of the state ­Republican Party.

The ruling ranks of the state party have largely lined up behind either Rubio or Cruz. Minnesota U.S. Reps. John Kline and Erik Paulsen back Rubio, as do former Gov. Tim Pawlenty and former Sen. Norm Coleman. A block of fiscally and socially conservative state House Republicans are with Cruz. After winning Iowa largely with support from evangelical Christian Republicans, Cruz is hoping to pull off a similar feat in Minnesota.

Rubio’s best bet is winning over moderate Republicans turned off by Cruz’s deep conservatism and by Trump’s flamboyant approach on the campaign trail.

“I think he is the most arrogant, rude, narcissistic bully I’ve ever seen in politics, and I’ve been following politics a long time,” Nancy Amerman, a retired Northfield attorney, said of Trump. “I’m completely baffled by his appeal.”

Amerman drove to Minneapolis on Tuesday for Rubio’s rally at the Hyatt Regency, saying she thinks the Florida senator could broaden the GOP’s appeal with nonwhite and younger voters.

A Trump win in Minnesota would likely be taken as a sign that his momentum has become unstoppable. Amerman said her views against abortion would make it impossible for her to vote for a Democrat in November but that she’s also not willing to vote for Trump, either.

In recent days, several former Minnesota elected officials came out in support of Trump. One is former Hennepin County Commissioner Mark Stenglein, an independent who thinks Trump’s abrasiveness is overstated.

“He truly wants to bring jobs back to this country,” Stenglein said. “Does he say it in a rough way? I guess so. Does he have a huge ego? All those guys have a huge ego.”

Another Trump supporter is Brian LeClair, a former GOP state senator from Woodbury who briefly worked on Pawlenty’s gubernatorial staff. “I would love to see Trump win here,” said LeClair, who runs his family’s insurance business. Many issues Trump has emphasized resonate with his own time in public service, he said.

About two weeks ago, LeClair signed up to volunteer. Since then, he’s been making nightly calls to fellow Republicans urging them to caucus for Trump on Tuesday night.