As President Obama prepares to kick off a battleground state sprint for Vice President Harris, some observers say the trip opens up an opportunity for President Trump to brand Ms. Harris and her allies as politicians of the past and a party of “yesterdays.”

Mr. Obama is “a popular figure, certainly in the Democratic Party, there is excitement around him, and then that also comes with quite a bit of fundraising power as well. But he’s also the past,” a Republican strategist, Matthew Bartlett, tells the Sun. “This is a candidate that was first elected almost two decades ago.”

As voters are looking towards who the “change candidate is,” Ms. Harris is pulling campaign support and approval from the likes of not only the Obamas but former Representative Liz Cheney and former Vice President Dick Cheney, he adds. 

“Right now, people are looking towards the future of the country. This is talk of yesterdays when this election is going to be about tomorrows,” Mr. Bartlett says. “So I think Donald Trump has some power, some energy, by saying that he is going against the grain. He is not the establishment, he continues to be outside Washington. And when all these endorsements pile up for Kamala Harris, he has a way of making political jujitsu and turning it to his own favor.”

Mr. Obama’s campaigning for Ms. Harris will kick off in Pittsburgh, Pennsylvania on October 10, in what will be the start of a 27-day blitz through swing states before Election Day, a senior Harris campaign official, reported by multiple news outlets, said. Mr. Obama, who gave a speech earlier this year at the Democratic National Convention, is popular with Americans: recent YouGov polling suggests that 57 percent of American adults have a favorable opinion of him, and 53 percent would likely vote for him if he was running for president this year. Fundraising efforts featuring Mr. Obama have raised $76 million in the presidential campaign, Axios reported. 

Asked if the upcoming campaign blitz could be an “October surprise,” like some of Mr. Obama’s supporters are suggesting, Mr. Bartlett says “This is an October shrug of the shoulders.” 

“Barack Obama campaigned hard for Hillary Clinton, campaigned for Joe Biden,” he says. “This is nothing new. He and his wife were stars of the Democratic convention after being the invisible hand that helped push Joe Biden out of the campaign.” Although it’s “mixed or unclear” if this will pull new voters, he adds “I don’t think that there’s a single American in this country that has been waiting on their decision between Harris or Trump and now that Barack Obama has weighed in, that they will follow.”

Other observers agree that the trip won’t necessarily affect swing voters, given that Mr. Obama’s party is the party in office. 

“I don’t think it will move the needle with undecideds, because they tried this in 2016 when he was still the sitting president, it wasn’t successful,” a former communications director for President Trump’s campaign, Marc Lotter, said in a CNN interview.  One critical difference, he says, is that now “nearly two-thirds of the American people still think our country’s headed down the wrong track. So going out there and saying that Kamala’s the new way forward? Well she’s the way of right now — difficult to sell.” 

Ms. Harris and Trump are within less than 2 percentage points of each other in all seven battleground states — Arizona, Nevada, Wisconsin, Michigan, Pennsylvania, North Carolina, and Georgia — RealClearPolitics polling averages indicate. 

Asked what type of messaging he’d expect from Mr. Obama on the campaign trail, Mr. Bartlett says he will likely go back to “hope and change, ‘08, to try to reignite that dream.”

“Now, with a new candidate, Kamala Harris, there absolutely is some energy and power to that,” he says, “but it is still a challenge, because she is the incumbent, because Democrats have been in power for the better part of 20 years here. So, it’s very hard to say that you are the change candidate when you are currently holding office.” 

A senior advisor to Mr. Obama was not immediately reachable by the Sun for comment, nor was a representative of the Harris campaign.