Democratic candidate Rob Quist delivers his concession speech in Missoula, Mont., after losing to Republican candidate Greg Gianforte on Thursday in Montana’s special House election to replace Ryan Zinke, now President Trump’s interior secretary. (Tommy Martino/Associated Press)

Democrats received a strong reminder from Montana voters that it takes more than just liberal outrage against President Trump and the GOP agenda to win seats that lean toward Republicans.

It takes serious candidates and a policy agenda of their own.

Their nominee, Rob Quist, hailed by liberal activists as a cowboy poet, delivered what most observers in Washington felt was an average performance in a race that was closely watched even before the Republican nominee was charged with assaulting a reporter on the eve of Thursday’s special election.

Some Democrats have responded to Trump’s victory, which they believe resulted at least partly from fame derived from his reality-television career, by searching for their own unique candidates. But after receiving just 44 percent of the vote, Quist may demonstrate the limitations of quirky, first-time candidates.

The showing also raises the stakes for Democrats in the June 20 runoff election for the race to replace Tom Price, the health secretary whose former House district north of Atlanta is seen as political ground zero this season because of its more competitive nature than other special elections held so far.

There, Jon Ossoff, a 30-year-old neophyte and former congressional staffer, is locked in a dead heat. Now more than ever, some party strategists fear that if he cannot put the race away ahead of June 20, late-breaking voters will not view him as a serious enough alternative in these politically turbulent times.

What Montana showed was the need to field candidates with backgrounds that appeal to voters who have tended to back Republicans in congressional races. It’s not necessarily an ideological requirement to be a centrist — serious candidates, such as Sens. Bernie Sanders ­(I-Vt.) and Elizabeth Warren (D-Mass.), can reside at the edge of the ideological spectrum. But they nearly always need more gravitas than Quist brought from a decades-long career as a guitar player in a popular bluegrass band in the Mountain West.

There are exceptions, of course. Sen. Al Franken (D-Minn.) is one — although it’s worth noting that Franken spent his first eight years in office avoiding the comedy shtick he was known for on “Saturday Night Live” because he recognized the need to get serious fast.

Of the three special elections, Quist clearly delivered the worst performance, based on a measure crafted by the smart analysts at the Cook Political Report. Democrats received 49 percent in the initial balloting in Price’s old district and almost 47 percent in the race in southern Kansas, better than Quist’s 44 percent.

Moreover, based on recent presidential races, the Kansas nominee performed 12 percentage points better than an average Democrat would have been expected to show, according to Cook. In Georgia, Democrats performed seven percentage points better than an average nominee.

Quist outperformed an average Democrat by just 5 percent. And he lagged woefully when compared with Montana’s Democratic governor, Steve Bullock, who won by four points in November against Republican Greg Gianforte — the businessman who beat Quist on Thursday despite being charged with assaulting a reporter the night before.

Democrats in Washington saw that as justification for their decision to invest only $500,000 in the race, dismissing Quist as a candidate who had a hard ceiling of about 43 to 45 percent among voters in their internal polling.

“DCCC took a smart chance with its investments, refused to waste money on hype,” Meredith Kelly, communications director for the Democratic Congressional Campaign Committee, wrote in a Friday memo.

Because it was a special election, Quist won the nomination at a party convention where the most liberal activists held sway, rather than a broad statewide primary.

The complaints about money are misguided when comparing this race to the Kansas special election. There, Democrats nominated another Sanders acolyte, James Thompson, who ran in a more conservative district than Quist, on a shoestring budget of $1.4 million. He received nothing close to the $500,000 Quist got from the DCCC.

Yet Thompson took a larger share of the vote than Quist, who raised and spent more than $6 million.

Perhaps if Montana Democrats had found a nominee with Thompson’s profile, they would have been better served.

Homeless as a teenager, Thompson enlisted in the Army and used the GI Bill to finance his education, serving as a civil rights lawyer for 13 years before launching his long-shot bid for Congress.

In their early recruiting for the midterms now 17 months away, Democrats have tried to thread this needle. They are tapping into the anti-Trump energy with first-time candidates who can appeal to anti-establishment progressives — but also with personal backgrounds that will demonstrate a serious devotion to governance intended to appeal across party lines.

This has produced an early focus on military veterans more closely aligned with Thompson’s background.

In the suburbs east of Denver, Jason Crow is a former Army Ranger and local lawyer running in a district where Democrats have underperformed year after year. In a similar district outside Philadelphia where Democrats have failed to put together strong challengers, Chrissy Houlahan is an Air Force veteran who helped run a basketball apparel company and worked in the nonprofit sector.

Beyond candidate recruitment lies a deeper question about the party’s agenda and whether Democrats need an update on their policy proposals.

Quist aggressively painted Gianforte as someone who would support Republican efforts to dismantle the Affordable Care Act without ensuring protections for those with preexisting conditions.

Ossoff has been hitting his opponent, Republican Karen Handel, for her efforts to deny funding for Planned Parenthood, while promising to be a problem solver who will work across the aisle to deliver results.

But there has been very little in terms of a specific Democratic agenda should they win the 24 seats needed to take back the House majority next year.

On Thursday, House Minority Leader Nancy Pelosi (D-Calif.) and Senate Minority Leader Charles E. Schumer (D-N.Y.) joined Sanders at an event to endorse his proposal to create a $15 minimum wage, something Sanders touted in his 2016 presidential campaign.

It showed party leaders were drifting toward the Vermont socialist’s economic views, but it is likely to do little to generate votes come November 2018.

Raising the minimum wage is an issue that always polls off the charts. But Democrats have pushed this issue in three straight elections, and it has done next to nothing for their candidates, because most voters want a lot more than a minimum-wage job.

Democrats might pull off the win in Price’s seat, but if they are going to ride a wave all the way to the majority, they probably need more experienced candidates than Ossoff and Quist — and with a sharper message than Ossoff’s introductory ad a few months ago.

“I’ll work with anyone to do what’s right for our country,” he said.

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