Updated Tuesday, 10:03 a.m.
It's been the story since Trump was elected.
Dueling, massive crowds showed up in Washington in January 2017: on one day, supporters of the newly inaugurated president; and, the next, an enormous gathering of opponents for the Women's March, with largely women leading the resistance.
A year-and-a-half later, that dynamic has played out in the early contests of this year's crucial midterm primaries. President Trump and the allegiance he's inspired among his base, as well as the outrage he has stirred on the left — particularly among Democratic women — have been two of the dominant storylines of 2018.
And now we enter the busiest stretch of the primary season, beginning with eight states holding primaries Tuesday. Just how busy will June be? Almost two thirds of the country, 31 states, will have voted by July overall, 71 percent of House races will be set and just over half of Senate ones.
Here are the four big messages voters have been sending with their votes so far in the 2018 midterm primaries:
1. The Republican Party is Trump's party now
President Trump continues to dominate news coverage and wields more influence in his party than anyone else — and Republicans running for office know it. Anyone who thought Republicans, fearing Trump's historically low approval ratings, would run away from this president were wrong — in primaries, anyway.
That may change in the fall when some of these candidates need to tack to the middle, but, right now, they're with their president. Why? Because GOP voters approve of Trump at record levels.
Several GOP candidates have hitched their wagons to Trump, sensing that's what their voters want, from candidates in Indiana who tried to out-Trump each other, to one in West Virginia who said he was "Trumpier than Trump" after the president told GOP voters to vote for anyone other than him. And speaking out against the president can present dangers. Look at Rep. Martha Roby in Alabama, who drew a crowded primary field because she criticized the president after the Access Hollywood tape came out before the 2016 election.
That has meant a Republican Party that is increasingly fashioning itself a party of one. "There is no Republican Party. There's a Trump Party," former House Speaker John Boehner said last week. "The Republican Party is kind of taking a nap somewhere."
One of the men vying to become the next House speaker, California GOP Rep. Kevin McCarthy, told CNN that the party's evolution is a good thing. "Well, I would think it's changed for the better," he said in response to Boehner's comment.
McCarthy cited the country's relative peace and prosperity under Trump. And Trump has certainly benefited from that, as well. His approval rating, for example, has gone from 37 percent in December to almost 45 percent now, according to the RealClearPolitics average of polls.
The question is whether that improvement will be enough for the Republican Party and its candidates, who are facing historical midterm challenges because so much of the enthusiasm is with the party out of power.
2. Democratic women are running and winning
Speaking of that enthusiasm, in primary after primary so far, it's been Democratic women making a statement. So far, more than 40 percent of House Democratic nominees have been women, according to NBC News.
A record number of women are running for the House and Senate in 2018. Overall, 417 women have filed to run. But nearly three times as many women have filed to run as Democrats than Republicans (310 to 107), according to the Center for American Women and Politics at Rutgers University.
So far, 159 total women have appeared on primary ballots in these early contests. Of those, 80 percent (126) have been Democrats.
Overall, 74 women have won primaries, and the lion's share (85 percent) have been Democratic women.
Cut another way, half of the Democratic women running in primaries so far have won (63 out of 126), while a third of Republican women have won (11 of 33).
So when people talk about the year of the woman, so far, it's been the year of the Democratic woman.
3. It hasn't been a good year to be a congressional Republican
Only one incumbent has lost a primary so far. That was Republican Robert Pittenger, from North Carolina, who was upset by an underfunded Baptist minister. Democrats think that could open up the seat as a target in the general election.
Other Republican congressional candidates have been denied job promotions. From West Virginia to Indiana to Idaho, that's been the case. Instead, what voters seem to value in Republican candidates is being an outsider businessman. Mike Braun captured that in Indiana, winning the GOP nomination for the Senate by running ads showing him walking around the state with cardboard cutouts of his similar-looking opponents, both of whom were congressmen.
There have been a record number of retirements among House Republicans, and it's looking increasingly likely that the GOP House conference is moving even more toward the right-wing Freedom Caucus, as the Washington Post's Dave Weigel reports.
4. Democrats' intraparty fight hasn't amounted to much — yet
As much as the Trump wing has flexed its muscle on the GOP side, the same can't be said for the Bernie Sanders wing of the Democratic Party, at least not yet anyway.
Progressives got a win in Nebraska, defeating a former congressman with a more liberal candidate, but that is looking more and more like an aberration rather than a trend. The left has had opportunities in Texas and Pennsylvania, for example, but those challenges fizzled.
Progressives, however, believe they have pushed Democrats on the issues. For example, many Democratic candidates are now talking about Medicare-for-all and a $15 minimum wage.
Are Democrats showing their pragmatic side, or have progressives just not hit their groove yet? After all, there's still plenty of irritation among them with the establishment wing of the party.
Check out what happened when Democratic National Committee Chairman Tom Perez endorsed New York Gov. Andrew Cuomo over Cynthia Nixon of Sex and the City fame. Not everyone on the DNC leadership team was on board with the decision.
"The Democratic Party should not intervene in the primary process," DNC Deputy Chairman Keith Ellison said in a statement after learning of Perez's endorsement. "It is our role to be fair to all contestants and let the voters decide."
The bottom line is: Democrats are unified, for the most part, against Trump. That may be enough to make gains in 2018, but a fight is coming on the direction of the party — whether it's in this year's midterms or in two years, in what's already shaping up to be a very crowded 2020 presidential field.
ARI SHAPIRO, HOST:
Today is the biggest primary day of the year. Voters in eight states from New Jersey to California are going to the polls, and their choices could determine which party controls Congress. NPR's lead political editor Domenico Montanaro is following the races and joins us now in the studio. Hey, Domenico.
DOMENICO MONTANARO, BYLINE: Hey, Ari.
SHAPIRO: So California's the biggest of these eight states where people are voting today; safe to say it has the most on the line.
MONTANARO: It does and not just because of its size but because there are seven seats - seven House seats - currently held by Republicans that went for Hillary Clinton in the 2016 presidential election. And if you think about that, Democrats need 23 seats on net to take back control of Congress. So you're looking at, you know, a third, almost a quarter - I'm sorry - a quarter, almost a third of the seats that Democrats need to take back the House. But the problem that they have here is that in three of these seats, Democrats are worried they won't even get a candidate through to the general election.
Now, really, they're most worried about one of those seats. That's because they have a top-two system in California where the top two vote-getters move on to the general election regardless of party. This is California - means lots of Democrats. Lots of Democrats are running in those seats, which means they could all split the vote and make a path for two Republicans to get through.
SHAPIRO: The jungle primary, they call it.
MONTANARO: That's what some people call it.
SHAPIRO: Beyond California, what races are you watching closely tonight?
MONTANARO: Well, you know, I do think that the House and that question of whether or not Democrats will take back the House is the big question. So when I look at another tranche of seats that are available for Democrats to sort of try to make some inroads, I look back across the country at New Jersey because New Jersey's got a handful of seats, four in particular, that Democrats are trying to flip. And just like in California, these are well-educated, affluent, suburban districts for the most part, places that Democrats are going to need to win. That's where the road leads to the majority in 2016 is through these suburbs.
SHAPIRO: There's been a debate through this primary season of whether President Trump is doing more to help Republicans or to turn out Democrats who are voting against President Trump's party. Where do you see him having an impact tonight?
MONTANARO: Yeah, and I should say 2018, not 2016.
SHAPIRO: (Laughter) Right, of course.
MONTANARO: But I think one place where the president's having an impact, you know, just because this particular congresswoman had come out against this president and after the "Access Hollywood" tape came out, Martha Roby in Alabama drew a stiff primary challenge.
SHAPIRO: She's a Republican.
MONTANARO: She's a Republican and because she said that President Trump - she wasn't going to vote for him because he - you know, because of the "Access Hollywood" tape. Her district, though, went by 30 points for Trump. So we're going to see if being able to speak out against President Trump is allowed or if it's punished tonight.
SHAPIRO: A measure of how much the Republican Party has become the Trump party. So stepping back, we are well through the 2018 primary season. After tonight, it will have been I think 21 states that will have voted. What have we learned so far?
MONTANARO: Yeah. We're about a quarter of the way through the primary season. And, you know, look; the two main storylines that have developed in this Trump presidency have been Trump's takeover of the Republican Party, as you noted, and that backlash that's been stirred among women in particular. And all of that has carried over into these primaries. We've seen Democratic women in particular send a real message at the polls, not just in voting but in winning. You've had a lot of women running and a lot of Democratic women winning at the polls, which is pretty fascinating. And you've also seen a lot of Republicans really hew very closely to President Trump. And, you know, that has been a huge change for the kind of ideology that they've talked about - lots on guns, lots on immigration - big changes from past elections.
SHAPIRO: NPR's Domenico Montanaro, and we will continue to check in with you later on tonight. Thanks a lot.
MONTANARO: It's going to be fun. Thanks. Transcript provided by NPR, Copyright NPR.