Three big-name political insiders have been targets of the activist, outsider wings of their parties.
And yet all three — Republican Sens. John McCain of Arizona and Marco Rubio of Florida, as well as Florida Rep. Debbie Wasserman Schultz, a Democrat — appear safe in their primary battles for re-election Tuesday.
McCain has been holding off a challenger running to his right on immigration; Rubio is well ahead of a candidate fashioning himself in the mold of Donald Trump; and Wasserman Schultz, the former Democratic National Committee chairwoman bedeviled by the progressive left, is favored to beat back an opponent funded by former Bernie Sanders supporters.
It's all remarkable in this year of discontentment with politics as usual. In Wasserman Schultz's case, she stepped down from her chairmanship of the DNC after emails revealed the party's appearing to favor Clinton. Millions of dollars poured into the coffers of Wasserman Schultz's opponent, Tim Canova, a college professor. But Wasserman Schultz is well-known in her district, and it went overwhelmingly for Hillary Clinton in the primary.
It's an even bigger deal for Republicans. They nominated the ultimate outsider for their presidential nomination — Donald Trump. Yet, down the ballot, those same voters are on track to stick with incumbents against conservative, outsider challengers in every Senate GOP primary election this year.
The fact that insiders are likely headed for big wins on the GOP side is one of the more surprising outcomes in a year that has seen Republican voters seemingly eager to uproot the establishment.
There are several examples:
-- New Hampshire GOP Sen. Kelly Ayotte, who faces a Sept. 13 primary challenge, is favored.
Other GOP incumbents facing primary challenges this year have won handily:
-- Sen. Lisa Murkowski, R-Alaska, won her Aug. 16 primary with 72 percent of the vote. She has come a long way to rebound among Alaskan GOP voters, who defeated her in the 2010 primary at the height of the Tea Party movement. (She mounted a write-in campaign that year and won.)
-- Conservative activists initially thought they could oust Alabama GOP Sen. Richard Shelby in his March 1 primary. But he dispatched his opponent and secured 65 percent of the vote.
-- In Indiana, establishment favorite Rep. Todd Young handily defeated Rep. Marlin Stutzman in the Senate GOP primary 67-33 percent even after Stutzman was backed by many of the same activists who helped oust incumbent GOP Sen. Richard Lugar in his 2012 primary.
The nonpartisan Rothenberg Political Report notes that of the 19 Republican senators who have already won primary elections this year, none of them won with less than 61 percent of the vote.
Conservative activists can claim one Senate victory this year, but it may be a shallow one. In Colorado, Darryl Glenn won the GOP primary with 37 percent and with the support of conservative activists. He faces incumbent Democratic Sen. Michael Bennet this November. But Glenn has been unable to dent Bennet's double-digit polling lead. Election forecasters favor Bennet to win re-election, because Glenn hasn't expanded his appeal beyond conservative voters in a swing state.
Kyle Kondik, an elections analyst with the University of Virginia's Center for Politics, said Republican voters have focused their anti-establishment energy this year toward the top of the ticket. Senators continue to benefit from one of politics' oldest rules: It's hard to beat an incumbent.
"History tells us that these upsets are few and far between," Kondik said. "Republicans don't seem to like their leaders right now, and they don't value experience very much, but that was really about the presidential race. These incumbents have so many advantages."
Jenny Beth Martin, co-founder of Tea Party Patriots, agrees. "I think the most important thing is there's an ironclad rule of politics that you cannot be somebody with nobody," she said. "We've seen relatively few challenges to the incumbents, because they have lacked either the name ID or the funding to pay for television ads and mail pieces to increase their name ID."
Incumbent advantages do include high name identification, deep pockets and party support to get out the vote. McCain and Rubio are benefiting from all of those factors.
Arizona: McCain's leading primary challenger is former state Sen. Kelli Ward, who has led a spirited — and, at times, controversial — challenge to the Senate's sixth-most-senior Republican.
Ward has run to McCain's right on immigration, aligning herself with Trump. She has also questioned his age and fitness for office, wishing him happy birthday Monday on national television to highlight that he turned 80.
Florida: Likewise, Rubio, who surprised many when he decided to run for re-election at the last minute despite pledging not to, is favored to win in a crowded primary field. His top challenger, wealthy businessman Carlos Beruff (pronounced beh-ROOF), is trailing by double digits in the polls. Beruff has invested millions in the race and campaigned as a Trump ally in a state Trump won handily in the presidential primaries.
Still trying to figure out the Trump effect on the GOP
Marty Cohen, a political science professor at James Madison University, said the down-ballot disconnect in the primary contests suggests that Trump's effect on the Republican Party may be exaggerated.
"I think it shows the general shallow nature of Trump's support within the party and the weakness of his campaign apparatus," Cohen said. "I just don't see there being any sort of grass-roots organization for candidates like him, or for candidates who seek to espouse the benefit from what he did."
Trump has also endorsed McCain and Rubio in their primary fights, depriving their primary opponents of critical political oxygen. Tea Party Patriots' political arm also endorsed Rubio.
Other outside conservative groups, like the Club for Growth and the Senate Conservatives Fund, have played a quieter role in the 2016 primaries.
The primary victories, however, do not mitigate the bruising general election battles ahead in which Senate Republicans are on defense in the fight for the majority.
There are about a dozen Senate races that make up the November battleground. Democrats are defending only one seat while Republicans are defending up to 11.
RENEE MONTAGNE, HOST:
This is a presidential election year like no other, as we keep hearing, and it could turn out to be a pretty big year in congressional politics too. Voters go to the polls today in Florida and Arizona to nominate candidates in two of the year's most competitive Senate races. NPR congressional reporter Susan Davis is here to give us a preview of these primaries. Good morning.
SUSAN DAVIS, BYLINE: Good morning, Renee.
MONTAGNE: Let's start in Arizona where John McCain is seeking a sixth term in the Senate, and he's facing, for him, something of a competitive primary race, isn't he?
DAVIS: He is. You know, McCain is favored to win his primary today. He's facing a challenge from former state Senator Kelli Ward, who has run at him from his right. In the closing weeks of the campaign, she's run a really aggressive campaign. She's called McCain old and weak. He turned 80 yesterday, so that his age has been an issue in this campaign. Although making age an issue in a state where many of the voters are retirees is not always the best strategy. So he is favored to win.
He's going to face Democratic Congresswoman Ann Kirkpatrick in the general election. And, you know, as you said, this is going to be a tough race for McCain. He's in a very difficult position where he needs to not alienate all of these Trump voters who elected Trump in the presidential primary there but maintain enough of that McCain mainstream appeal to win swing voters in November.
This is going to be one of the more competitive Senate races. It's also a bit of a firewall for Republicans. They really need McCain to win if they have a chance to hold onto the Senate. If he loses, there is no doubt that Republicans are losing the Senate.
MONTAGNE: Oh, well, so turning to Florida, there's Marco Rubio, and he, of course, had repeatedly said he was giving up his Senate seat. But after losing his shot at a presidential run, Rubio changed his mind, which, I gather, energized Republicans fighting to keep control of the Senate.
MONTAGNE: So how's he doing?
DAVIS: He's doing well. You know, he decided, as you said, he wanted his job back after all. And when he got back in, it got most of the Republicans out of that primary except for a wealthy businessman named Carlos Beruff, who has also challenged Rubio from the right. The problem that Beruff has is that Rubio has been endorsed by Donald Trump, and he's been endorsed by many tea party groups. So that really took a lot of oxygen out of his campaign. Rubio is going to - you know, on the Democratic side, they also have a primary today.
There's two congressmen facing each other. The favored is Patrick Murphy over Alan Grayson. Grayson has faced a number of ethical challenges, and Democratic Party leaders do not want him to win the nomination. Murphy's favored. A Rubio-Murphy race would be one of the most competitive races this fall. As of right now, Rubio's running a little bit ahead of Murphy, but this is going to be a top Senate race.
MONTAGNE: And there's another high-profile Democratic race in Florida. Debbie Wasserman Schultz, who was recently pushed out as Democratic National Committee chairwoman, she is facing a serious challenge from a more liberal rival who is aligned or was aligned with Bernie Sanders. Does her challenger have a chance?
DAVIS: Probably not, but this race has become more about a proxy war between the Hillary Clinton-Bernie Sanders divide in the Democratic Party. As you said, she's angered many progressive activists who have flooded this race and helped her opponent raise $3 million. Her opponent is a guy named Tim Canova. He's a political newcomer. He's never run for office before, and he's got a lot of buzz.
But the reality is this district still heavily favors the incumbent. It's an older district. It's a whiter district. It has a high, sizable Jewish population that Wasserman Schultz has remained incredibly close to. And this is a district that Hillary Clinton won by nearly 40 points in the March presidential primary. So this is still a place that is reflective of her and her district, and she's favored to win. And if she loses, it would probably be the biggest upset of the year.
MONTAGNE: OK. Well, lots to keep an eye on today. Susan, thanks very much.
DAVIS: Thanks for having me.
MONTAGNE: That's NPR congressional reporter Susan Davis. Transcript provided by NPR, Copyright NPR.