I mentioned on Twitter yesterday that I am regularly asked by smart national folks how GOP Sen. Dean Heller is still in the race.

They see his approval numbers, his occasional rhetorical hiccups, the rising Democratic tide and wonder how poll after poll shows the race with Democratic Rep. Jacky Rosen is a dead heat.

As usual, I have more thoughts than can be contained to 280 characters, so let’s explore this further.

Nevada is often referred to as a purple state and occasionally as a light blue one. That’s because of recent history – three consecutive Democratic presidential candidates have won here. The Reid Machine proved formidable, causing Nevada blue waves in 2008, 2012 and 2016.

But those are presidential campaign years, when turnout is above 80 percent and Hispanic turnout is higher and crushes Republicans. Ask John McCain or Mitt Romney or Donald Trump.

This is a midterm, where turnout is much lower. In 2014, the last midterm, it was 46 percent. Compare that to 2016’s turnout: 77 percent.

(Heller, who has never lost, actually won in 2012, a presidential year, bucking the blue wave and defeating then-Rep. Shelley Berkley, by 12,000 votes.)

Democrats have been fearsome in recent presidential years here, but in midterms they struggle to get their voters out. Even though they have maintained registration advantages, their share of the electorate has been much different in midterms.

The disparities the last two cycles are stark:

2016: The Democrats had 49 percent of the overall electorate and the Republicans had 36 percent.

2014: The Republicans had 42 percent and the Democrats had 37 percent.

In 2010, when turnout was up for a midterm (65 percent) because of then-Sen. Harry Reid’s remarkable campaign, the GOP still had a 1 percent share advantage.

So it is a struggle for Democrats in off-years, which is why Heller is so close in the models.

The Democrats had a disastrous year in 2014, with no candidate for governor and no one to draw voters to the polls, and they lost every constitutional office, the Legislature and their bench. That’s partly why Reid tabbed Rosen – not his first or 15^th choice – to run for Congress and now for Senate.

So despite his upside-down numbers and the Trump drag, Heller could still win because of the likely Democratic dropoff. Indeed, strategists might say the Democrats are – because of this history – fortunate to be so close here and in the governor’s race.

Democrats have built the Clark County registration numbers up above a 130,000 advantage over the Republicans, and if they can turn out their voters there in the first cycle in the post-Reid-Machine-era, they could win both of the top contests.

But they also know the facts: They realize Heller has never had to give a concession speech because his campaigns have been as good as any in state annals at defining opponents. Sure, he has had some luck, too –then-Rep. Shelley Berkley almost surely would have defeated him six years ago if not for that House Ethics probe being announced in the middle of the campaign.

Team Heller and his allies scorched the earth until November, pushing undecideds to vote for “None of the Above” or third-party candidates, thus managing to eke out a victory.

They don’t have a House Ethics investigation to work with this cycle, but Rosen is so new (hence the “she’s a zero” meme) that they have a near-tabula rasa to work with.

Rosen will try to keep the focus on Heller – her ads generally have been superb -- and his multifarious positions on multifarious issues, especially health care. And Democrats will hope Heller keeps up his penchant for self-inflicted hiccups.

One thing to consider, too: Even though the outside money surely will favor Heller in the coming weeks, the costs of television have skyrocketed to 1,500-plus for a gross rating point of TV. There is not a lot of time left to buy – thanks, Question 3 – and what there is will be tremendously expensive and perhaps not as cost-effective as past cycles.

The Democrats probably feel good about where they are, especially because they have two candidates at the top who are at least of the quality of the GOP contenders – and that has not happened often in midterms here. And they are hoping that indies, who will be close to 30 percent of registration by November, will continue to lean against Trump and provide them with a decisive demographic advantage they don’t often see in midterms.

But Heller is alive and can never be counted out because of historical turnout patterns in Nevada and because of his record of invincibility.

Disclosure: Shelley Berkley has donated to The Indy. You can view a full list of our donors here.