By Jonathan Bernstein

Bloomberg View

No, Carly Fiorina isn’t going to be the Republican presidential nominee. But all it takes for someone to be chosen as a running mate is one nominee’s whim — as John McCain proved when he selected Sarah Palin in 2008. So how does the former chief executive officer of Hewlett-Packard stack up as a potential vice-presidential pick?

That’s a question for the political silly season, since Fiorina has qualified for the main event at the next round of Republican debates on Sept. 16.

When it comes to running mates, the chief requirements should be that they do no harm, and that they would make an acceptable president, if necessary. It turns out that all the modern vice-presidential candidates who have turned out to be problems have had one thing in common: None of them had previously been vetted by running a full presidential campaign.

Fiorina would be an unusual case: She will have run a presidential campaign but never held political office. Since Republicans will have plenty of other options for vice president, it seems unlikely they would want to take a risk on her.

The main argument for her as a GOP vice-presidential candidate has been that it would help blunt the gender gap Republicans may face in running against Hillary Clinton. But women on their party’s tickets in the past — whether Republican or Democrat — didn’t make a difference with female voters (Palin in 2008 and Democrat Geraldine Ferraro in 1984).

In fact, there’s little evidence that the bottom of the ticket can help in the general election at all, beyond perhaps providing a small boost in his or her home state. And Fiorina certainly wouldn’t allow Republicans to carry California.

Then there’s the issue of serving as president, if need be. Fiorina (along with Ben Carson and Donald Trump) hasn’t developed the political governing skills necessary for success in the Oval Office. It’s possible she could succeed anyway, but why take the risk? Presidential failures exact a huge price on a party, both in electoral prospects and in lost opportunities to carry out favored policies (see: Jimmy Carter, George W. Bush).

And party groups who care about policy likely won’t be happy if they’re asked to trust someone who hasn’t demonstrated loyalty in lower office.

Maybe Carly Fiorina will overcome all of these odds. Somehow, I doubt it.

? Jonathan Bernstein is a Bloomberg View columnist covering U.S. politics.