Even if Democrat Conor Lamb loses Tuesday's too-close-to-call special election in Pennsylvania, his party can declare victory. They gave Republicans a run for their money in classic Trump country: mostly white, working-class, high-school-educated suburbs in a swing state. This Pittsburgh-area congressional district voted for President Trump by 20 points in 2016. Now, the race is so close we may not know the winner for days.

That Democrats even came close to winning this seat should buoy their optimism about their chances of taking back control of the House of Representatives this November. Here's why:

This isn't the kind of district Democrats need to win to take back the House of Representatives: There are nearly 120 more competitive congressional districts than Pennsylvania's 18th, according to a ranking by the nonpartisan Cook Political Report.

Those 120 congressional districts aren't all suddenly in play after Tuesday — there were unique factors about this special election that won't necessarily translate to November.

But the fact that Democrats were competitive in such a Republican-leaning district makes the 24 seats they need to net in November look much more feasible.

Well before this special election, Democrats were already optimistic they could win back a sizable number of the 23 seats controlled by House Republicans in districts that Hillary Clinton won in November. They were buoyed by coming close in special elections in deep-red Georgia and by winning a Senate special election in Alabama. Now, their confidence is through the roof that those 23 seats are in play.

“We can win everywhere,” an optimistic Democratic National Committee chairman, Tom Perez, said Wednesday morning on CNN.

Democrats are outperforming Hillary Clinton. In a non-presidential year: Depending on the final result in Pennsylvania, Lamb will have gotten about 20 more percentage points in votes than Clinton did, with all of her campaign's presidential might behind her.

Republicans argue that it's natural for the party out of power to perform well after a presidential election. But Democrats are performing really well.

According to data by left-leaning political blog Daily Kos, Democrats outperformed Clinton by 15 to 20 percentage points in 2017 special elections in South Carolina, Montana and Kansas.

At the statehouse level, Democrats have flipped some 35 seats since Trump's election and outperformed Clinton by massive margins such as 20, 30, 40 and even 50 percent in states where they don't normally win big, including Oklahoma and Missouri. The Daily Kos also finds that on average, Democrats are outperforming President Barack Obama's 2012 numbers in these districts.

There are signs that Democratic turnout is stronger than it normally is: Democrats traditionally struggle to get their voters to the polls for anything that's not a presidential election, but early evidence suggests the party might buck that trend this time. Early indications are that turnout was higher than usual in Pennsylvania's special election.

And in last week's Texas primaries, Democrats managed to get 1 million voters to the polls — their best showing in a midterm primary there in 16 years. (Though, as I point out here, Texas Republicans got 1.5 million voters out to turn out, tempering any hope of a blue wave in Texas.)

Democrats are doing well in polling: If you had to choose right now between electing a Democrat or a Republican to Congress, even if you didn't know their names or policies, whom would you choose? In polls over the past month that have asked this, voters say they would choose a generic Democrat over a generic Republican by an average of 10 points. Election forecasters say Democrats need a six- to eight-point advantage in this kind of poll, called a generic ballot, to win a House majority. Democrats have consistently been ahead of that range.

Democrats had a chance to get more comfortable with red-state Democratic messages: Democrats from Alaska to Colorado have been arguing since Clinton's loss that their wing of the party cannot be ignored if Democrats ever want to regain power in Washington and the states. And yet, they have watched as the party's more liberal branch impresses purity tests upon its leaders:

  • Sen. Dianne Feinstein (D-Calif.), who has said Trump could be a “good president,” didn't receive the endorsement of California's Democratic Party in her bid for reelection. The snub boosts her primary challenger, State Senate leader Kevin de León, who has literally accused Trump of not having a soul.
  • House Democrats' campaign arm has also refused to support an antiabortion congressman running for reelection in Chicago, Rep. Daniel Lipinski (D-Ill.), as he faces a primary challenger from the left.

But in Pennsylvania, Democrats had no choice but to support a candidate who was decidedly not liberal. Lamb said he would not vote for Rep. Nancy Pelosi (D-Calif.) as the leader of House Democrats, neutralizing a Republican attack against him, and he campaigned on loving to shoot his gun.

If Democrats want to expand their chances of winning a majority, it makes sense to compete in conservative districts with candidates who are more conservative than the center of the party. And with Lamb's campaign, they may have a playbook on how to do it.