Here's a mind-blowing truth-bomb for you: The goal of a political campaign is to get elected. It's not to pass legislation, it's not to advance a cause. It's to cobble together enough votes to reach that magic 50.00001 percent margin that propels you into office.

There's an old political saying that applies to politics generally but to campaigns in particular: There are no permanent allies, only permanent interests. The permanent interest of a campaign is winning. And the allies that can get you there may evolve.

This week, we saw a predictable-but-unexpected demonstration of that point as Sarah Palin endorsed Donald Trump. It's not a weird occurrence in the context of 2016, but it's a weird evolution in the context of recent American history.

The New York Times' Nick Confessore described that odd evolution in under 140 characters.

We can visualize it in photos, too.

1. Donald Trump invited Hillary Clinton to his 2005 wedding and donates to her Senate reelection. (In 2008, he called her a "terrific woman.")

2. Clinton, of course, supported her husband's vice president, Al Gore, when he ran for president in 2000. (The photo below is from a "Women for Gore" rally that year.)

3. Gore's running mate that year was Joseph Lieberman.

4. Lieberman, after leaving the Democratic Party, endorsed John McCain when McCain ran in 2008. (Had Clinton won the nomination, would he have endorsed her? We may never know.) (But, no, he wouldn't have.)

5. McCain's running mate in 2008? Sarah Palin.

6. Who now backs Trump.

A long chain that takes Trump from partying with the Clintons to this.

Former Alaska governor Sarah Palin, left, hugs Republican presidential candidate Donald Trump after endorsing him during a rally at Iowa State University on Tuesday in Ames, Iowa. (Mary Altaffer/AP)


Top photo via Getty Images. Other photos from the Associated Press.