At a DFL field office housed in the shell of a former car dealership on University Avenue in St. Paul, a loud makeshift rattle and cheering punctuated the steady chatter of phone calls promoting the Democratic cause come November.

"Another volunteer agreed to a shift," said Lucas Smith, 21, explaining the cacophony. Since June, the Macalester College student has been recruiting for the DFL, which is trying to mobilize a campaign army behind Gov. Mark Dayton's bid for a second term.

In a political career spanning decades, Dayton for the first time is building a re-election machine. For months, his campaign and the DFL Party have raised funds as they lay the groundwork for a November clash with Republicans.

The race crystallized last week when Jeff Johnson, a Hennepin County commissioner, won the Republican primary in a four-way race. The GOP is in the midst of a comeback effort after years of statewide losses. While DFLers have had months to plan for November, Johnson must pivot quickly from a party primary where he triumphed by winning over a small subset of the party's most faithful — just 56,000 ballots in a state of more than 3 million registered voters.

Not yet a proven fundraiser, the commissioner has to show Republican donors that he's a good investment. Johnson will have plenty of competition from within his party — dozens of other GOP candidates in Minnesota and nationally who are trying to capitalize on the unpopularity of President Obama.

"I do believe there is a motivated Republican base," said Gregg Peppin, a senior adviser to Johnson. "Our goal is to be synergistic with the party, so that the people we know are Jeff people, we figure out a way to channel that energy."

While Johnson, who served six years in the Legislature, tries to sell a more conservative approach to state budgeting, Dayton will defend his first-term push for upper-class income tax hikes — and the extra spending on education and other programs that revenue enabled.

Dayton himself has been edging slowly toward the campaign trail. But behind the scenes, his campaign, his party and allied groups have been methodically preparing for months. In July, the party opened 15 field offices across Minnesota where volunteers are charged with building local support.

The Dayton campaign has also gotten an assist from Minnesotans United, the political action committee that grew out of the successful effort to defeat the 2012 gay marriage ban and then pass the 2013 law that made same-sex marriage legal. Minnesotans United assembled one of the most sophisticated grass roots operations the state has seen in years, and has vowed to protect allies like Dayton, who signed the gay marriage bill.

"We encourage our volunteers to volunteer on behalf of the governor," said Richard Carlbom, the strategist who ran Minnesotans United. The group has shared its lengthy donor list with the DFL.

And as DFLers busily plot strategy, Dayton is taking full advantage of the natural benefits of incumbency, appearing in public as governor rather than candidate.

Just in the last week, Dayton visited Mankato and Marshall to celebrate construction projects partly funded by the state capital bonding bill. He toured private businesses in both cities, and showed up for the grand opening of a new upscale outlet mall in Eagan.

"His schedule has been focused on doing the job he was elected to do," said Katharine Tinucci, Dayton's campaign manager. Tinucci was Dayton's chief spokeswoman for much of his first term, and also worked for his 2010 campaign.

Dayton's aides said that explicitly political events would continue to be light on his schedule for the remainder of August, and then pick up after Labor Day. Still, he made some time for politicking last week: On Wednesday, between official stops, he popped into a Mankato meet-and-greet for DFL state House candidate Jack Considine.

Dayton leads in funding

In the days after his Tuesday primary win, and following a Wednesday morning news conference with his vanquished rivals, Johnson took a breather from public appearances to concentrate on fundraising.

Right now, Dayton's advantage is notable: By the end of the last reporting period on July 21, he had raised and spent more than Johnson, and had more left in the bank. While Dayton was sitting on about $847,000, Johnson had only $123,000 cash on hand.

"We gotta raise a lot of money in the next 12 weeks," Johnson said after the primary. Dayton's campaign will also try to accelerate its fundraising.

Both candidates have agreed to state-enforced contribution and spending limits that will allow them each to raise a total of about $4 million, and in exchange receive a public subsidy for their campaign. For Dayton, that's a big contrast to 2010, when he poured $3.7 million of his personal wealth into the race.

To reach the $4 million limit, Johnson would have to raise about $250,000 weekly between now and the election. Campaign manager Scot Crockett said the actual fundraising goal is a bit more modest.

"This is going to probably be somewhere north of $2 million for us, how high I'm not sure yet," said Crockett, a veteran operative with a long resume in Minnesota and national Republican politics. From 2012 to 2013, Crockett was executive director of Tea Party Patriots, one of the most prominent national groups associated with that movement.

But as November approaches, Johnson will be competing for campaign funds with state House Republicans, who are making a major push to recapture the majority from the DFL, and with other conservative candidates and causes.

Spending in the governor's race is also likely to be eclipsed by the U.S. Senate battle between incumbent DFL Sen. Al Franken and Republican challenger Mike McFadden, meaning the candidates for governor will have to push to be noticed amid a likely flood of Senate ads on TV, radio and online.

The Minnesota Republican Party, still emerging from several years of scandal and financial troubles, has a lot riding on Johnson's candidacy. As the endorsed GOP candidate in the primary, Johnson's win gives the party bragging rights — but the real test comes in the fall matchup.

After a few days of fundraising, Johnson will make frequent public appearances that could include a news conference this week and possibly several public forum-style events, Peppin said.

Republicans also have opened more than a dozen field offices statewide to boost local organizing. Party Chairman Keith Downey said he believes the party is poised for a revival, and that a major emphasis has been improving its get-out-the-vote effort after realizing Democrats have outmatched them on that front in recent election cycles.

"The state party is focused on the ground game this year, which is something we believe we have upgraded," Downey said.

Outside groups an unknown

A major unknown in the still-forming race is spending by third-party groups on behalf of one candidate or the other. Dayton and the DFL have a strong ally in the Alliance for a Better Minnesota, which is funded by major DFL donors and union allies, and which has spent more than $10 million since 2007.

Last week, the group quickly launched a TV ad blasting Johnson on the grounds that tax cuts he supported as a member of the state House a decade ago could instead have been spent boosting education programs.

These independent groups are able to spend money on candidates with fewer limits than the campaigns themselves, but by law are prohibited from coordinating messages or tactics with the campaigns.

For Republicans, veteran operative Ben Golnik has been running the Minnesota Jobs Coalition, which in the last year has prodded at Dayton's budgeting policies as harmful to private enterprise in the state.

"I think we've established ourselves as the lead group holding Dayton accountable," Golnik said, noting that his group's camera-toting trackers have already filmed more than 100 hours of Dayton speaking in public. Some of those clips could slip into TV commercials or other advertising.

"Our donors are certainly interested in keeping the heat on Dayton," Golnik said. A roster of well-known GOP contributors have helped fund the group, including McFadden and Scott Honour, one of the Republicans Johnson defeated last Tuesday.

Still, Downey said he believed DFL-aligned independent groups were likely to outspend those allied with Republicans. That's been the case in recent history.

"There is every indication they will do the same this year," he said.

Ricardo Lopez • 651-925-5044 Patrick Condon • 651-925-5049