The establishment struck back.
Two weeks after House Majority Leader Eric Cantor's primary loss to a little-known and underfunded tea party challenger rocked the Republican Party, incumbent and mainstream GOP candidates came out on top in several high-profile primary showdowns.
In Tuesday's marquee race, longtime Sen. Thad Cochran of Mississippi narrowly fended off a fierce primary challenge from state Sen. Chris McDaniel, who edged Cochran in the primary three weeks ago. Cochran's victory might have come from crossover Democratic voters -- courted by the senator -- who cast ballots in the runoff.
Cochran was joined by Rep. James Lankford, who easily won the primary in Oklahoma over two other major candidates who enjoyed tea party support in the race to succeed a retiring senator. Former Rep. Bob Beauprez, considered the mainstream pick in Colorado's GOP gubernatorial primary, topped three other candidates. And former South Carolina Attorney General Henry McMaster, the ultimate insider, won a landslide victory in the state's Republican lieutenant governor runoff.
In another high-profile showdown, Democratic Rep. Charlie Rangel of New York, who was first elected to Congress 44 years ago, claimed victory in what he says will be his last campaign. But Rangel's opponent, state Sen. Adriano Espaillat, who nearly ousted Rangel in the Democratic primary two years ago, wasn't conceding the tight race early Wednesday morning.
And in Maryland, outgoing Gov. Martin O'Malley, a potential 2016 Democratic presidential contender, wasn't on the ballot but might have been the biggest winner of the night.
Here are five things we learned from Tuesday's primaries.
1. Creative coalition: Tuesday night's results illustrate the unscripted political realities that play out in particular states on Election Day.
So who would have thought that in today's political climate -- and in a deeply red state like Mississippi -- a 76-year-old long-time Republican incumbent could beat back a serious tea party challenge?
And who would have thought that he could do it by courting the African-American vote while touting his longevity in Washington.
Cochran's allies worked aggressively in recent weeks to reach out to Democrats, especially African-Americans who make up 37% of the state's population.
But McDaniel argued the tactic was a stretch, saying in his election night speech that Cochran showed his willingness to win at any cost, even diluting the party if he needed to.
"There is something a bit unusual about a Republican primary decided by liberal Democrats," he said. "So much for principles. I guess they can take some consolation that they did something tonight for once again compromising, for once again reaching across the aisle, for abandoning the conservative movement."
The question is whether the strategy can be applied beyond Mississippi. McDaniel warned Tuesday night that it certainly could.
"Today the conservative movement took a backseat to liberal Democrats," he said. "If it can happen here, it can happen anywhere. And that's why we will never stop fighting."
2. Experience still counts: Along with Cochran, Rangel also used his experience in Washington to sell himself to voters.
"I think because of the confidence (the voters) had in me, with my service and their belief with the decision they had to make, that I was their best choice," Rangel told reporters.
For Cochran's part, the senator actively reminded voters of his work to secure federal funds for programs used widely in the state.
It's not the kind of message that Republicans tout in these days of fiscal conservatism. But in this case, it worked for Cochran.
He also stressed his position and influence in the Senate, saying if Republicans win control of the chamber, he would likely become chairman of the appropriations committee, a seat that could help him get even more money for the state.
3. Oklahoma blunder? Cochran's comeback was the big shocker of the night, but there was another surprise in Oklahoma, where Rep. James Lankford cleared 50% of the vote and skipped a runoff against his top rival, Oklahoma House Speaker T.W. Shannon, in the race to replace retiring Sen. Tom Coburn.
Many observers figured the primary was surely headed to an August runoff.
Shannon, an African-American who is a member of the Chickasaw Nation, had all kinds of national buzz. He was endorsed by a batch of tea party groups, and by Ted Cruz, Mike Lee and Sarah Palin. Cruz even cut an ad for Shannon, but it wasn't enough.
In fact, the help Shannon received from outside conservative groups, namely the Senate Conservatives Fund and Oklahomans for a Conservative Future, may have backfired.
After Lankford, a member of the House Republican leadership who voted to raise the debt ceiling last year, was attacked in TV ads from the two pro-Shannon groups, Coburn weighed in with a pseudo-endorsement, praising Lankford as "a man of absolute integrity." Lankford used the kind words in a television ad that ran late in the primary and may have helped push him over the top on Tuesday.