Democrats performed 20 points better in a Kansas special election in a deep red congressional district. They very nearly won outright another special election in suburban Atlanta. Republicans are spending millions to try to hold onto a seat in a Montana special election later this month.

And now, with longtime Rep. Ileana Ros-Lehtinen (R-Fla.) retiring in 2018, Democrats' task of trying to flip a Miami-area congressional seat — something that absolutely has to happen if they want to take control of the House of Representatives in 2018 — just got immensely easier.

It's still very early, but by nearly every measure we have of a party's electoral strength, we see positive signs for House Democrats in the 2018 midterm elections.

Now, the caveat: Does that mean House Democrats will wrest back control of the House of Representatives from Republicans for the first time in six years? If I could tell you that, I'd probably be making a lot more money as the world's only political pundit who could see into the future.

But we can say this: There is a grass roots energy on the left that the party hasn't seen since the early Obama years. And, just as the tea party movement helped Republicans in 2010, the activism could help Democrats reach some of their most aspirational goals in November 2018, like taking back the House. It feels as if we're seeing the early makings of a wave election.

The next step for Democrats is more challenging than coming close to winning a Georgia election or hoping that more Republicans in Democratic-leaning districts retire. So far, Democrats' success has happened independently of the party. The Democratic candidates' stronger-than-expected performance in Kansas and Georgia was driven almost entirely by dissatisfaction with President Trump, who is the least-popular president at this point in time in modern history.

Democrats have to find a way to capture this potent anti-Trump energy and have it materialize into actual votes a year and a half from now. And they have to do it in places that may not be as anti-Trump country as Ros-Lehtinen's district, like Virginia and Minnesota and Colorado and Texas.

Ros-Lehtinen is sitting in one of 23 Republican-controlled districts that also voted for Clinton. Hers was the most Democratic-leaning. Not all of them favored Clinton by double digits; according to data from liberal election analysts DailyKos, Rep. Ryan Costello (R-Pa.) won his Philadelphia suburbs district by more than 14 points, and Clinton won it by 0.6 percentage point.

GOP districts that also voted for Hillary Clinton. (Stephen Wolf / DailyKos)

“There's no question that there is tremendous enthusiasm right now and that needs to be maintained,” Jesse Ferguson, a Democratic strategist with experience in House elections, told The Fix in April.

Take last month's special election in Georgia to replace Health and Human Service Secretary Tom Price as a measure of how successfully Democrats are organizing. Once Democrats recognized grass roots momentum was elevating a 30-year-old with no legislative experience, they gave Jon Ossoff everything they had. He fell just shy of winning a majority of the vote outright against a fractured Republican field, and he will face a much-tougher runoff against just one Republican in June.

Was that a victory for Democrats' organizational skills? Or a failure? Depends on whom you ask.

Ros-Lehtinen's retirement presents the same kind of challenge for Democrats, just in a different form. After nearly three decades in the House, the moderate Republican says she's stepping down to be with her family and grandchildren. But she's also leaving a Miami-area district that voted for Hillary Clinton over Trump by 20 points.

Ros-Lehtinen's seat is exactly the kind of seat Democrats need to win in 2018 to have a shot at flipping control of the House. In Miami, it definitely helps Democrats that they won't have to try to take down a well-known incumbent. But can they repeat that 23 times over — and hold onto all their potentially vulnerable Democratic members?

In other words, Democrats need absolutely everything to go in their favor to have a shot at taking back control of the House.

So far, almost every measure we have is going in their favor. But we've got a long way — 555 days — to go.