Keller: Do vice presidential picks matter to voters?

The opinions expressed below are Jon Keller's, not those of WBZ, CBS News or Paramount Global.

BOSTON - Vice President Kamala Harris selected Minnesota Gov. Tim Walz to be her vice presidential running mate on Tuesday. Do VP picks really matter to voters?

"Historically," said former President Donald Trump recently, "the vice president in terms of the election has no impact, virtually no impact."

Expert says VP choice has an impact

But Professor Emeritus Joel Goldstein of Saint Louis University, perhaps the nation's preeminent expert on the vice presidency, calls that claim "false." The vice presidential choice "has an impact on the way in which we view the people who selected them, how they go about making decisions, whether they make good decisions," he says.

For instance, Bill Clinton's 1992 choice of fellow Southern Baby-Boomer Al Gore underscored his core political message. "The choice of Al Gore really reinforced the idea of generational change," says Goldstein. Meanwhile, John McCain's 2008 selection of Sarah Palin undercut his claim to be a more sober, seasoned Obama alternative.

Choice reveals political priorities

And the professor says the current nominees' choices reveal their political priorities, with Trump's pick of J.D. Vance placing conformity over party unity. "Of all the choices, he was the one who was most prepared to articulate President Trump's MAGA approach and philosophy," says Goldstein.

Kamala Harris appears to be looking for help filling gaps in the Democratic coalition. "She's choosing somebody who I think she expects may be able to speak in a way that resonates to a type of voters who've been leaving the Democratic party," says Goldstein.

These choices matter at the margins, says the professor. But still, as Trump puts it: "If you like me, I'm gonna win. If you don't like me, I'm not gonna win."

Is J.D. Vance persuading any skeptics to like Trump? So far, the polls suggest otherwise. Will Tim Walz warm anyone up to Harris? We'll soon see.

But while it's easy to laugh off the second banana as meaningless, it's also a mistake. They are, after all, just a heartbeat away.