Among the many confusing things about Republican hopeful Ted Cruz's decision to announce Carly Fiorina as his running mate on Wednesday is this: She's simply not that popular.

There's not much recent polling on Fiorina, who bowed out of the GOP race in February. But with the exception of a brief spike in popularity last fall, she made little impact on voters, peaking at less than 8 percent nationally before falling to just above the 2 percent mark.

A late January YouGov/Economist survey found that 53 percent of Republicans viewed Fiorina favorably and 34 percent viewed her unfavorably, for a net rating of +19. That's decent, but lower than GOP voters' opinions of Cruz and fellow candidates Ben Carson, Mike Huckabee, Marco Rubio and Donald Trump.

This pick is an attempt to mute Trumps appeal to voters who want a political outsider, but it is unlikely to have much impact," Patrick Murray, the polling director for Monmouth University, said in a statement. "Republican voters already have an outsider candidate they like."

"This will help Cruz dominate a couple of news cycles before next weeks make-or-break primary in Indiana, but it is likely to have a limited impact on swaying voters or, more importantly, convention delegates," Murray added.

Cruz has consistently struggled to pick up support beyond the GOP's most conservative faction , making little leeway with primary voters who describe themselves as anything less than "very conservative." But polls from Iowa and New Hampshire , where Fiorina competed, don't show those voters holding a particular affinity for her, either.

And though Fiorina ran for a Senate seat in California six year years ago, this doesn't appear to carry any outsized weight in that state's upcoming primary. While she handily won her Senate primary in 2010, the last survey to include her as a candidate in this year's presidential race showed her polling at about 3 percent in the Golden State.

Fiorina is even less popular with a national audience. As of February, her average rating among all Americans was a net -18, making her nearly, though not quite, as disliked as Cruz himself, who stands at -23.

More importantly than any of that, research suggests a presidential hopeful's choice of a running mate doesn't make much difference, even for candidates who are actually their party's nominees.

"Except in extraordinary circumstances, citizens vote based on the presidential candidate, not the running mate," political scientists Christopher J. Devine and Kyle C. Kopko wrote earlier this week .