It works both ways. Just ask Milton Wolf, Chris McDaniel and Matt Bevin.
Even as Senate Republicans facing primary challengers have come under increased scrutiny in recent months and have stumbled in some cases, the tea party conservatives looking to unseat them have rapidly begun to feel the impact of a thorough examination from the media and the GOP establishment, resulting in their own notable setbacks.
Part of the reason tea party challengers are feeling heat like never before is that incumbents and their allies have simply had more practice. Before the rise of the tea party in the 2010 midterms, sitting senators were unseated only four times in more than a quarter century. It's happened four more times since 2010.
Where they failed in the past to recognize the threat posed by these challengers, now senators and supporters are redoubling their efforts to avoid getting taken down by the right as conservatives have flooded the field with ambitious challengers who idolize conservative rabble-rousers like Sens. Ted Cruz (R-Tex.) and Mike Lee (R-Utah). (Half of the GOP senators running for reelection this year are facing primary challengers.)
The result, strategists say, is a sharper opposition research effort and a more robust supplementary movement from deep-pocketed groups.
"Republicans felt burned by Senate challengers and incumbents that weren't ready for prime time in the last cycle," said Ron Bonjean, a former House and Senate GOP leadership aide. "Many Republicans felt that we could have taken the Senate majority back if it wasn't for rookie mistakes made by candidates. The combined opposition research efforts of outside groups and investigative journalists have created a political 'Hunger Games' that could eventually weed out weak primary candidates who could implode over time.
The latest example of the pendulum swinging back against an insurgent challenger came in Kansas over the weekend. The Topeka Capital Journal reported that Wolf, a radiologist challenging Sen. Pat Roberts (K-Kan.), had posted graphic X-ray images online of gunshot victims and others, and cracked jokes about the images.
Just weeks earlier, it was Roberts who was playing defense against the revelation that he pays a modest monthly rent to stay with supporters when he in Kansas and rents out the home he owns.
Bevin's past has also come under sharp focus in Kentucky, where he is trying to unseat Minority Leader Mitch McConnell (R). Politico recently reported that Bevin had once supported the TARP bank bailout program he likes to criticize sharply in the campaign. In Mississippi, McDaniel's initial wavering about whether he would have supported a Hurricane Katrina relief bill prompted criticism from his opponent, Sen. Thad Cochran (R) and regional editorial writers.
Cochran's situation is an example of how some Republicans have marshaled money and resources in order to micro-target races and protect incumbents. A super PAC called Mississippi Conservatives has formed in order to help him, even though it is barred from coordinating with his campaign. The group has already been targeting McDaniel on television. McDaniel has his own allies, national tea party groups, such as the Club For Growth and the Senate Conservatives Fund.
Digging into challengers' pasts is only part of the job for incumbents and their allies. Flubs, mismanaged campaign tactics and signs of disinterest in the state and/or the conservative movement can erase momentum in a hurry.
The main protagonist in this cautionary tale is Richard Lugar. The long-serving Indiana Republican senator lost to Richard Mourdock in 2012 after running a campaign at which many national strategists shook their heads. Lugar was unable to shake stories about his residency, thumbed his nose at the tea party, and relied on a formula that many Republicans saw as outdated and a poor fit for the 2012 climate.
Roberts's residency status may expose him to the same kind of problems Lugar experienced. And Cochran's recent remarks that he doesn't "really know a lot about" the tea party as well as his praise of President Obama in 2008 could haunt him against McDaniel.
With Republicans in eager pursuit of the Senate majority this cycle with no margin for error, it's especially important for them to to field candidates for the general election who can win. To the National Republican Senatorial Committee, that means making an extra effort to protect incumbents in safe GOP seats and avoiding what happened in Indiana, where Mourdock turned out to be disastrous general election candidate and handed what once looked like a safe Republican seat to Democrats.
"The first step is protecting every Republican seat that's up and ensuring we don't waste resources," said NRSC spokesman Brad Dayspring.
Conservative activists say the stiff push back from incumbents and their allies against the tea party threats reflects worry on their part and could backfire.
"We've seen this type of thing before from the establishment. What's different now is the NRSC has hit the panic button much earlier than in previous cycles. They hope it will destroy these conservative candidates, but it will probably only anger the grass roots and cause them to work even harder to defeat these incumbents," said Matt Hoskins, executive director of the Senate Conservatives Fund.
A battle for control of the Republican Party is alive and well. This much is clear: Those who are in office right now are not going to fight it sitting down.