Why would one candidate's super PAC support a rival?

Republican presidential candidate, Sen. Ted Cruz, R-Texas, pauses while speaking at a business round table at Draft Sports Bar & Grill in Concord, N.H., Monday, Aug. 31, 2015. (Photo by Cheryl Senter/AP)
Republican presidential candidate, Sen. Ted Cruz, R-Texas, pauses while speaking at a business round table at Draft Sports Bar & Grill in Concord, N.H., Monday, Aug. 31, 2015. 
 
To briefly recap, Ted Cruz has a super PAC called Keep the Promise that exists, naturally, because it supports Cruz's national ambitions. That's the point of a super PAC -- to raise money to bolster the candidate that the group and its donors want to see win.
 
But in a campaign-finance filing, amid Keep the Promise's routine expenditures, there's a $500,000 payment to CARLY for America. And if CARLY for America sounds familiar, that's because it's the name of the super PAC that's backing Carly Fiorina, one of Ted Cruz's many rivals for the Republican presidential nomination.
 
And that's pretty odd. Why would one candidate's super PAC write a six-figure check in support of another candidate? The Washington Post reports that the Federal Election Commission is wondering the same thing.

People were left scratching their heads in July when Keep the Promise 1, one of a conglomerate of super PACs funded by deep-pocketed Cruz supporters (the others are cleverly named Keep the Promise PAC, Keep the Promise II and Keep the Promise III; don’t strain yourself, guys), revealed in its financial disclosures a $500,000 donation to Fiorina’s campaign. Keep the Promise 1 had a healthy $10 million on hand from an $11 million donation from hedge fund CEO Robert Mercer as of the end of June. But it only spent $536,169. A little for legal services. A little for surveys. And a whole lot for Fiorina. Even the Federal Election Commission is perplexed. [...] So, the FEC, as it does, sent a letter Wednesday asking for “a brief statement or description of why each disbursement was made.”

The letter appears to have gone out this week, and the super PAC did not respond to the Washington Post's request for comment.
 
As for CARLY for America, NBC News reported yesterday that the Fiorina operation is facing questions about the possible blurring of legal lines.

CARLY for America is the super PAC; Carly for President is the campaign. The difference between the two is so subtle that the candidate herself occasionally directs voters wanting to learn more about her campaign to her super PAC website: "Check out Carly-for-America-dot-com," Fiorina says. The difference between the two is also close enough to have warranted a slight name change after running afoul of FEC regulations that bar independent expenditure committees -- those not authorized by a candidate -- from using a candidate's name in their title. After the FEC flagged the violation in a letter to the super PAC, "Carly for America," a direct reference to the candidate, became the acronym: "Conservative, Authentic, Responsive Leadership for You (CARLY) and for America.

If you have any guesses as to why Cruz's super PAC would write a big check to Fiorina's super PAC, let me know in the comments section.