Months ago, as the 2014 election cycle was shaping up as a good one for Republicans, the Democrats in North Carolina resolved to buck the trend. They had a great deal of help — from a friendly news media, from left-wing interest groups furious with the conservative reforms enacted by the GOP legislature, and from deep-pocketed donors and independent-expenditure groups that outspent their counterparts in the U.S. Senate race between incumbent Kay Hagan and challenger Thom Tillis.

The Democratic effort was massive. It was expensive. It was brash, sometimes even to the point of being obnoxious. And it was, in the end, a failure.

Tillis never sustained a lead in the public polls. In fact, his strategists admitted that Tillis never sustained a lead in his own polling. The campaign’s strategy of tying Hagan tightly to Obama and holding her accountable for his unpopular economic, health care, and foreign policies was widely criticized as unimaginative. Tillis also drew criticism for lackluster fundraising and for allowing Hagan to use his legislative record to turn the Senate contest into “a school-board race,” as one Hagan aide put it with a sneer.

Who were these critics? Some were Republican consultants on the outside looking in. Some were Democratic activists trying to shape the conventional wisdom to their advantage. Some were liberal journalists who shed the illusion of objectivity and openly rooted against Tillis because they wanted the race to serve as a public referendum against Gov. Pat McCrory and the Republican legislature.

I’ll admit that I had my doubts about the prospects for Tillis winning the race, too. But those doubts began to weaken during the month of October, as I saw him recover from Hagan’s barrage of attack ads in September while she struggled to move her average poll numbers above 45 percent. A key reason why so many Democratic partisans and liberal commentators discounted the Tillis rebound is that they fell prey to confirmation and selection bias. Any poll that showed Hagan ahead was greeted as “high-quality” and “independent.” Any poll that showed the race tied or Tillis ahead was dismissed as “shoddy” and “biased.”

In my tracking, I included every public poll. During the last week of the race, I counted 12 of them. Averaging the results produced an exact tie: 45-45. Public Policy Polling, a Democratic firm that uses automated survey technology, produced three of the 12. All showed Hagan ahead. Three other firms with Republican ties or conservative leanings also did robo-polls: Gravis, Harper, and Vox Populi. Harper, which was set up explicitly as a Republican competitor to PPP, produced a +2 edge for Tillis. That turned out to be the most accurate poll of the race.

As I talked to national reporters about the race, most were incredulous when I explained that many North Carolina Democrats didn’t care very much about Kay Hagan’s fate or which party would control the U.S. Senate. What they really wanted to do was defeat House Speaker Thom Tillis as part of their quest to regain control of state government. They hoped a Tillis loss coupled with significant Democratic gains in the legislature this year would built momentum for broader gains in 2016, including the defeat of McCrory, the state’s first Republican governor in 20 years. In this, the Democrats were doubly disappointed. Not only did Hagan lose, but most of the candidates they put up in competitive legislative races fell short. Republicans actually expanded their majority in the North Carolina Senate and lost a net of just three seats in the North Carolina House. Conservatives also defeated sales-tax increases on the ballot in several counties, including populous Mecklenburg and Guilford. Only the Democrats’ takeover of the county commission in Wake County, the second-most-populous in the state, brightened what was an otherwise dismal disappointment for a party that, until just four years ago, seemed firmly ensconced as North Carolina’s governing majority.

At its core, the Democratic strategy was predicated not just on turning out its base — which it did fairly well — but also on convincing previously Democratic voters to rejoin its coalition. They swung for the swings, and they missed.

John Hood is chairman of the John Locke Foundation.