The handful of big ranked-choice elections across the country offer one clear takeaway for Minneapolis mayoral campaigns: Ignore second- and third-choice votes at your own peril.

With just over a week before Election Day and no clear-cut leader, the campaigns are running largely without a playbook as they scramble for support to replace Mayor R.T. Rybak in one of the largest races nationally to ever use ranked-choice voting. Only two larger U.S. cities, Oakland, Calif., and San Francisco, have used ranked-choice voting in a competitive mayoral contest.

"The dynamics of this race are unlike anything we've seen," said Jeanne Massey of FairVote Minnesota, which advocated for the process that accounts for voters' second and third choices when determining a winner.

In Oakland, the candidate who garnered the most first-choice votes in 2010 lost the election because supporters of losing candidates favored his main opponent for their other choices. In San Francisco, a political novice front-runner won in 2011 after working to appeal to a broader coalition of voters.

"We're talking to a lot of local and national experts about how those played out," Mark Andrew's campaign manager Joe Ellickson said of the Bay Area races. "And elements of those are impacting our decisionmaking."

Thirty-five candidates are vying to succeed Rybak, eight of them with structured campaigns. The open seat is the city's biggest test of ranked-choice voting, which was used just once before in 2009's sleepy election.

Under the process, which is used in 11 communities nationally including St. Paul, voters select three candidates in order of preference. Candidates with the fewest votes are eliminated by round. If a voter's top choice is nixed, their vote is then redistributed to their next-choice candidate. It continues until a candidate garners more than 50 percent of the remaining votes.

'Nobody called it'

Oakland is the most vivid example of how ranked-choice voting can upend an election. In that race, front-running candidate Don Perata's lead was dubbed "all but insurmountable" in a newspaper headline two days after the election as other rounds were being counted. Surprising everyone, he lost to City Council Member Jean Quan.

"The Oakland race was a lightning strike," says David Latterman, a San Francisco political consultant. "Nobody called it. I certainly didn't."

Quan's victory is often attributed to the alliance she struck with several other candidates who coalesced around the goal of beating Perata, a polarizing and well-financed former state senator who outspent his opponents. Quan and her allies held a joint news conference accusing Perata of trying to buy the election, and Quan instructed her supporters to list her City Council colleague Rebecca Kaplan as their second choice.

"We're trying to get a candidate other than Don," Quan was quoted as saying at a forum.

Perata took a commanding 9-point lead based on voters' first choices, but Quan picked up an overwhelming majority of Kaplan's remaining votes when Kaplan was eliminated. Polls show that Quan has since become a deeply unpopular mayor, however.

A similar situation isn't quite playing out in Minneapolis. While Andrew boasts the most establishment support, there is no clear front-runner and candidate alliances have been subtle.

Don Samuels' campaign manager, Patrick Layden, sees the Oakland race as a "clear parallel" to Minneapolis, but he added that every race is different. "All you can do is hope that previous experience and other races give you some clue as to the possible outcomes," Layden said.

Some political gurus in Minneapolis see similarities in the 2011 race for mayor of San Francisco, the first competitive ranked-choice mayoral election in that city. Sixteen candidates vied for the seat, including recently appointed incumbent Mayor Ed Lee, who had never run for office before.

Second, third spots crucial

After vowing not to run, Lee entered a race already packed with well-known politicians in August and emerged as a front-runner. Some candidates went negative, but Lee was able to win after "dominating the Chinese vote and doing well with second and third choices throughout most of the city," according to an analysis co-authored by Latterman. It took 12 rounds to determine a ­winner, but Lee led on every one.

"The Ed Lee race showed that if you're at the top, you need to mind your p's and q's to make sure you take care of second- and third- place votes," said Andy O'Leary, Betsy Hodges' campaign manager

Another Bay Area contest with similarities to Minneapolis, though on a much smaller scale, was a 21-candidate 2010 race for a San Francisco Board of Supervisors seat that remained wildly unpredictable heading into Election Day. It took 20 rounds to determine a winner: Malia Cohen, who had been a third-place finisher on round one. Second- and third-choice votes helped propel her in later rounds.

Tony Hill, a longtime Minnesota political scientist now working at MIT, says the presence of many serious candidates on the Minneapolis ballot could set the stage for a similar outcome. "The fact that some of these people are there … has the potential to stir things up the way it happened in San Francisco," Hill said.

Opponents have tried unsuccessfully to repeal ranked-choice voting in San Francisco and Oakland — an editorial last year in the San Francisco Chronicle said it had produced "voter confusion and vacuous campaigns." Others have been successful, like Burlington, Vt., which repealed it after an incumbent mayor was re-elected in a tight race after placing second on the first round.

Despite earlier elections, Minneapolis 2013 is likely to be its own case study for ranked-choice voting experts across the country. In particular, the lack of a strong front-runner makes it unique.

"What happens will be watched very closely as it was in San Francisco," said Hill.

Ellickson, of the Andrew campaign, said they are studying several ranked-choice races because "we don't know the exact scenario that we're potentially looking at here in the final" days before the election.

Independent candidate Cam Winton said Minneapolis is charting its own course. "That's part of what's so exciting about this race," he said.

Eric Roper • 612-673-1732

Twitter: @StribRoper