Given that reality, Cruz needs to change the narrative of the race. Immediately. There are five and a half days until the Indiana primary and if Cruz loses to Trump there the nomination fight will be effectively over. And if nothing changes in the race in the Hoosier State, Cruz will lose.
Announcing Fiorina is a big swing at story-changing. Cruz has to hope that the coverage over the next few days — both in Indiana and nationally — will focus on Fiorina and why it was smart of him to pick her. Every second that cable TV and local media outlets spend talking about Cruz and Carly is a second that Trump doesn't dominate the conversation. And what recent history has told us is that when Trump dominates the conversation, he almost always wins.
This is rightly understood as a desperate attempt to re-take the momentum in the race before it's too late. To Cruz's credit, he's trying it. (I'm a big believer in leaving it all out on the field. If you are going to lose, lose with all of your best plays called. Or something.)
Now to the first question: Why Fiorina?
Let's take as a given that since Fiorina's campaign ended and she endorsed Cruz on March 9, the two have found out that they have a genuine rapport and share a vision for the country. And let's also assume that Fiorina has passed some sort of basic (or more-than-basic) vet by the Cruz campaign. (Remember that Fiorina not only ran for president in 2016 but also ran for Senate in 2010.)
What else does she bring Cruz? In order of importance:
* A woman. Trump's numbers among female voters — especially in a general election — are disastrous. Cruz has struggled to drive that message home in the primary but is clearly hoping that by elevating Fiorina to I'll-pick-her-if-I-can-pick-anyone status that Fiorina can help reach female voters who the Texas senator needs, not just in Indiana but going forward in the race.
* A Californian. Fiorina is a known commodity in California Republican circles due in large part to her 2010 Senate campaign which, although she lost, got better post-campaign reviews than the gubernatorial effort run by fellow wealthy businesswoman Meg Whitman. Cruz is banking on Fiorina as an able surrogate for him in California — both in front of the camera and behind the scenes — in advance of the state's June 7 primary. By that point, Trump should be nearing the 1,237 delegates he needs to be the nominee, and depriving him of a handful here and there in California congressional districts may be Cruz's only option. He believes Fiorina can help that cause.
* An attack dog. This works on a near-term and long-term basis. In the near term, Cruz now has an attack dog who has proven to be relatively effective in battling Trump. Fiorina's reputation on that front is largely built on a single exchange during a CNN-sponsored debate in September 2015 in which she appeared to get the better of the real estate mogul who has made comments about her face. (Yes, really.)
Long term — meaning if Cruz is the nominee — Fiorina is a potentially potent weapon to attack Hillary Clinton. In fact, during her own presidential campaign, Fiorina was, by far, the most willing to hit Clinton on personal matters — an approach she would likely continue if/when she was formally the Republican Party's vice presidential nominee. And, as a woman, Cruz likely believes Fiorina would have more leeway and be more effective in those attacks.
None of it is unreasonable. And if Cruz is going to pick a VP this far in advance of the party convention — and with so little certainty that he will ever actually be in a position to pick a second in command — he could do worse than Fiorina.
But make no mistake: This is a Hail Mary pass. It, like the deal that Cruz and John Kasich cut earlier this week, amounts to a tacit acknowledgment that if nothing changes in the race Trump is going to win.
Could it work? Sure. Sometimes Hail Marys get caught. But usually they get knocked down and the other team starts celebrating.