Voters cast early ballots at a voting center in Minneapolis on Sept. 23, 2016. The DFL is hoping to energize young voters. (The Minnesota Star Tribune)

The DFL in Minnesota and Democrats nationally feel a stiff breeze at their backs this election year, but they also face a potential problem: Their key voter groups are not as reliable in off-year elections, when the White House isn't up for grabs.

A DFL operative, granted anonymity to speak frankly about strategy, shared some Minnesota data with me: In 2012, among voters 18 to 34 years old, turnout was about 60 percent, compared to overall turnout of 76 percent. In 2014, just a quarter of younger voters turned out. If those voters had turned out at the same percentage as the total electorate in 2014, Minnesota would have recorded another 300,000 votes.

Those voters lean progressive. According to a March Pew Research Center survey, 57 percent of millennial voters say they are "consistently liberal" or "mostly liberal," while 12 percent say they are mostly or consistently conservative.

So, how to get them out? The DFL strategist tells me this is the year to do it. "There's something happening among voters who are not usually engaged in nonpresidential years," he said.

But the DFL will have to work for it, with candidates speaking to these voters about issues they care about that might otherwise get short shrift: college tuition and college debt, the environment, guns and health care for older millennials who are starting families.

Candidates and campaigns will need to go where these young voters are: Social and digital media. When Tim Pawlenty announced last week he was running for governor to seek a third term, the DFL-leaning Alliance for a Better Minnesota was all over social media, trying to define Pawlenty to voters too young to have formed an impression of him when he left office in 2010.

Although President Donald Trump has animated DFL voters since his inauguration, the lesson of 2016 is that being against Trump is not enough.

"There's certainly a lot to talk about with the current leadership of our national government, but that's not enough," the DFL operative said. "You need to inspire them about an election and what the possibilities are for the future," said the DFL strategist.

Young voters aren't the DFL's only focus. It wants to drive up turnout among people of color, while taking advantage of Trump's approval problems among women and suburban women voters in particular.

But young voters offer the biggest potential upside. Unfortunately for the DFL, they are about as reliable as the Minnesota weather.

J. Patrick Coolican • 651-925-5042 patrick.coolican@startribune.com Twitter: @jpcoolican