Why JD Vance's plan to follow Kamala Harris and Tim Walz on their swing-state tour is a big gamble

• JD Vance is set to follow Kamala Harris for three days on her swing-state tour with Tim Walz.
• Republicans are working hard to halt the momentum surrounding Harris' presidential campaign.
• But Vance could falter in his efforts, as his standing with voters remains low.

Vice President Kamala Harris is just hours away from embarking on a swing-state tour with her newly announced running mate Tim Walz, in an effort that's poised to be a major turning point for the Democratic ticket.

But if Sen. JD Vance of Ohio, the GOP vice-presidential nominee, has his way, Harris' time in the spotlight with Walz won't be an easy experience.

Vance plans to follow Harris for three days across four swing states as the presumptive Democratic nominee campaigns with Walz, according to a schedule shared with Politico . The rollout is especially important for Harris as she became the party's standard-bearer less than a month ago following President Joe Biden's exit from the presidential race.

The Ohioan is set to trail Harris in Philadelphia; Detroit; Eau Claire, Wisconsin; and Raleigh, North Carolina. And while Vance won't be headlining rallies, he'll be holding media appearances in the cities alongside voters critical of the Biden-Harris administration.

At first glance, Vance's trip may not seem like a high-stakes effort.

But it's a gamble.

Republicans want to blunt Harris' momentum

In recent months, former President Donald Trump had been leading Biden in most major national polls. And Vance's vice-presidential selection was seemingly aimed not at drawing in swing voters — who had been souring on Biden — but on firming up the Republican base.

But Biden's withdrawal from the race and Harris' ability to quickly rally the party around her caught the GOP by surprise. And it sapped any real bump that could have resulted from last month's Republican National Convention.

In recent days, Harris and Trump have been locked in a close race in national and swing-state polls, with the vice president pulling ahead in some of the surveys.

Enter Vance, who wants to halt any sort of sustained momentum for Harris as she stumps with Walz.

When Harris appears in key battlegrounds this week, Vance will be there to attack the Democratic ticket on local news and bring out conservative voters to sharpen criticism of Biden's record on issues such as the economy and immigration. The senator is seemingly aiming to get ahead of the news cycle to blunt a potential Democratic vice-presidential honeymoon period.

Vance's effort could make him even more unpopular

Since joining the GOP ticket last month, Vance's rollout has been a rocky one.

Vance already had a national profile because of his best-selling 2016 memoir, "Hillbilly Elegy." But before Vance was elected to office in 2022, he made a raft of controversial statements, and during one notable interview, he deemed some Democratic Party leaders to be " childless cat ladies " who didn't have a stake in the country's future.

Vance's past remarks and views on issues such as Ukraine (he opposes US funding for the conflict) haven't been a hit with voters. He boasted a minus-five-point favorability rating after the GOP convention. Last month, CNN reported that Vance had a double-digit unfavorable rating with voters in a group of Midwestern states that included his native Ohio.

So Vance's plan to lay into Harris and Walz will be a tricky balancing act. Vance doesn't have the highest standing with voters at the moment, and Harris now has an executive on the Democratic ticket with real appeal among working-class voters.

Vance may struggle to define Harris' views

Vance will be looking to draw attention to the GOP ticket when Americans will naturally want to learn more about Walz.

It'll be a huge fight for attention during a time when Harris could receive another polling bump based on the selection.

Republicans have sought to depict Harris as too liberal for the country and have pointed to her San Francisco Bay Area roots to make their case.

But so far, that argument hasn't proven effective with voters, and Walz is largely seen as a mainstream Democratic choice.

Vance will surely hammer Harris over her past support for more liberal proposals on healthcare during her 2020 presidential campaign. But Harris now has a record as part of the administration, and she can point to populist achievements such as capping the cost of insulin at $35 a month for many Americans on Medicare.

Some voters will applaud Vance's shadow tour of Harris' vice-presidential rollout, while others will view it as a stunt. Either way, Vance's itinerary shows that Democrats have all the momentum right now, and Republicans are doing whatever they can to stop it.

This story was originally published on August 5. It's been updated with information about Harris' pick of Walz .