Democrat Tim Walz and Republican Jeff Johnson were the big winners in straw polls for governor at Minnesota precinct caucuses Tuesday night.

In the Democratic-Farmer-Labor balloting, Walz, the 1st District congressman from Mankato, led the crowded pack with 31 percent of the votes with two-thirds the precincts reporting. State Auditor Rebecca Otto was in second place with 20 percent, followed by state Rep. Erin Murphy with 13 percent and former St. Paul Mayor Chris Coleman at 12 percent.

State Rep. Tina Liebling and former House Speaker Paul Thissen trailed behind in the single digits. Thirteen percent of the DFL attendees were not committed to any candidate.

Walz said the results left him “cautiously optimistic. … What’s encouraging is it’s looking like it’s pretty broad support across the state. It’s coming from all areas,” he told reporters at DFL Party headquarters in St. Paul. However, he quickly noted, “There’s nine months to November.”

At the Republican caucuses, Hennepin County Commissioner Johnson was the clear victor. With all precincts reporting, Johnson, the party’s unsuccessful 2014 candidate for governor, had 45 percent of the vote, followed by undecided voters with 16 percent.

Former state GOP Chairman Keith Downey was in third place with 15 percent, followed by school teacher Phillip Parrish and Woodbury Mayor Mary Giuliani Stephens tied with 12 percent each.

Johnson attributed his win to a number of factors, starting with “working extremely hard.”

But he noted that he finished third in the 2014 straw ballot months before he was endorsed for governor. So his victory Tuesday night “was not crucial” but helps “put me in a really good spot” to be endorsed again, Johnson said. He now plans to start “reaching out to people who aren’t Republican activists” to prepare for the November election.

The large number of undecided Republican voters might signal an opening for former Gov. Tim Pawlenty, who shook up the GOP field hours before the caucuses convened by announcing that he will leave the Washington, D.C.-based Financial Services Roundtable next month. That could clear the way for him to enter the governor’s race. Pawlenty, who left office seven years ago and then ran unsuccessfully for the White House, plans to meet with potential donors and other Republicans next week to discuss his options.

The straw polls were just beauty contests. Caucus-goers are not bound to the candidates they vote for.

But the balloting shows which candidates are most popular and have the strongest campaigns at the official start of the election season. Those contenders likely will get a boost in lining up support from party activists and donors.

The straw polls also are likely to start winnowing the large fields of candidates in both parties. Those who do poorly probably will be shunned as losers.

The candidates are running to succeed DFL Gov. Mark Dayton, who is not seeking re-election after two terms in office.

Straw polls have not been accurate at predicting who will be endorsed at state party conventions later in the season. During the last race for an open governor’s seat in 2010, for instance, Minneapolis Mayor R.T. Rybak won the DFL straw poll, and state Rep. Marty Seifert came out on top in the GOP balloting. But neither won his party’s endorsement that year.

Caucus-goers were scheduled to elect delegates to their party’s Senate district and county conventions, which in turn will elect state convention delegates who will endorse candidates for governor, two U.S. Senate seats, attorney general, state auditor and secretary of state. Congressional district delegates will endorse U.S. House candidates.

In Apple Valley, it was clear Tuesday night that a lot of caucus-goers turned out not because they were committed to any particular candidate, but because they wanted to be part of the process.

That was especially true for Kevin Ly, Benji Johnson and Eric Schmidt, Eastview High School seniors, who said they came to the Republican caucus to dispel the myth that all conservatives are older.

Bryan Aisenbrey, a Rosemount resident who has been caucusing for two decades, also wasn’t committed to any candidate. He mainly turned up to “see who was in the mix” for the governor and Senate races.

At Falcon Ridge Middle School, where DFLers were meeting, Gail Hoffmann said she came out in support of Walz for governor specifically because she thought he could beat a well-known candidate like Pawlenty. Walz has had success winning support in areas that have traditionally been difficult for Democrats, she said.

“I really want someone with a proven record who can influence areas that normally go red,” Hoffmann said. “Walz can get votes in rural areas.”

Democrats had their share of undecided caucus-goers too. Nasra Hassan, a Somali-born immigrant who lived in Kenya before settling in Rosemount, said this was her second caucus, but she did not have a preference for any candidates, yet.

Hassan was there to meet people and participate in the political process. She wanted to learn more about the DFLers’ positions on topics important to her — immigration was at the top of her list.

With half of precincts reporting, 17,655 DFLers had caucused. That was on pace to surpass DFL caucus turnout of 22,532 in 2010, the last time there was an open seat for governor.

“I’m really excited about the turnout,” state DFL Chairman Ken Martin said. “If this is any sign of things to come, this is a year of great turnout in the Democratic Party.”

About 11,000 Republicans cast votes in their party’s straw poll. That was far fewer than the nearly 20,000 who turned out for the 2010 GOP caucuses.

Both parties will hold state conventions June 1-3. Republicans will meet in Duluth, while DFLers convene in Rochester.

Chris Magan and Dave Orrick contributed to this report.