One-time hero and cranky old man John McCain has shown that it's possible to save your political career in American politics if you're willing to ditch all the principles you once championed.
When he sought the Republican presidential nomination in 2000 in a failing campaign against a total dud, George W. Bush, McCain preached tolerance and moderation, denouncing extremism. Bush hammered McCain with truly sleazy campaign dirty tricks. For years afterward the Arizona senator worked across the aisle to promote immigration reform, campaign finance reform and measures to combat climate change.
And then an open-mouth radio nutjob, JD Hayworth, did what Vietnamese torturers couldn't - he got McCain to grovel and abandon everything he once stood for. Out with immigration reform, ditch campaign finance reform, nix that nonsense about global warming. Out with all those principles, in with Lee Atwater-style campaigning.
Once McCain jettisoned his integrity he managed to float up to meet his Tea Party challenger and even pass the guy entirely. Arizona voters went to McCain by a handy margin. After all it was a no-lose proposition - Hayworth values in a McCain skin.