After a rocky start for Senator Vance on the national stage as the youngest vice presidential candidate in seven decades, Republicans are rallying around their untested nominee as he gets his bearings. President Trump has said he fully supports his running mate despite the criticism he has faced, even as old comments and sagging poll numbers hamper the GOP ticket. 

When Mr. Vance was nominated by acclamation at the Republican convention just more than two weeks ago, he was met with cheering — even some crying — fans on the floor. The honeymoon quickly subsided, though, after a number of controversial comments made years ago were brought to light online, leading the Minnesota governor, Tim Walz, to mint a new branding for the Ohio senator: He’s weird. 

Mr. Vance, in his role as a commentator and Senate candidate, has said a number of things that are catching the attention of activists and donors. He named Vice President Harris as one of the “childless cat ladies” who is “miserable” in her own life. He has called for higher taxes on those who do not have children, and even said that parents should gain an extra vote for every child they have. 

Senator Murkowski told Politico that the “childless cat lady” remarks — made on Tucker Carlson’s Fox News show in 2021 — were “offensive.” 

“If the Republican Party is trying to improve its image with women, I don’t think that this is working,” Ms. Murkowski said. 

Trump is so far undeterred and sticking by his running mate, despite the criticism. “He’s not against anything, but he loves family. It’s very important to him,” Trump told Fox News’s Laura Ingraham on Tuesday of the cat ladies comment. “He feels family is good, and I don’t think there’s anything wrong in saying that.”

“The Democrats are good at spinning things differently from what they were. All he said is, he does, like, I mean, for him, he likes family. I think a lot of people like family, and sometimes it doesn’t work out,” the former president added. 

In defense of Mr. Vance, conservatives and fans online have tried to take back the “weird” label and spin it onto Democrats. Mr. Vance himself wrote on X, “JD Vance is weird,” in quotes, and included a video of Ms. Harris announcing her pronouns at a CNN town hall when she was running for president in 2019. 

“The left wants you to believe that one of these people is ‘weird’ and that the other one is completely normal,” a Republican strategist, Greg Price, wrote, including a photo of Mr. Vance and his family, and a photo of Ms. Harris with a drag queen at the Naval Observatory. Another GOP strategist, Kingsley Wilson, wrote “JD Vance is weird” in an X post, accompanied by multiple photos of President Biden sniffing the hair of young girls. 

As Republicans, understandably, rally around their own, voters seem so far unconvinced by the young senator’s performance. According to a Reuters-Ipsos poll released on July 23, 32 percent of voters have a favorable opinion of Mr. Vance compared to 39 percent who view him unfavorably. That net negative of 7 percent makes him the most unpopular vice presidential candidate of a major party since 1980. 

His solo campaign events have been lackluster, often featuring strange one-liners and poor delivery of prepared remarks. On his first day of campaigning, he tried to crack a joke about how Democrats would try to make drinking Diet Mountain Dew racist somehow, drawing almost no response from the crowd. At a campaign event in Nevada, his stilted delivery of one line was caught by online observers, making him appear even more awkward. “When you fill up your … pump — when you fill up your tank at … the gas station, maybe you should send the bill to Kamala Harris,” he said. 

One of the greatest dangers Mr. Vance poses to the campaign, though, is his ties to the now-infamous Project 2025 program developed by the Heritage Foundation and more than 100 conservative groups, many of them with direct ties to the Trump campaign or the previous Trump administration. 

On Tuesday, the head of the organization, Paul Dans, announced he would step down, much to the Trump campaign’s delight.

“President Trump’s campaign has been very clear for over a year that Project 2025 had nothing to do with the campaign, did not speak for the campaign, and should not be associated with the campaign or the President in any way,” Trump’s senior advisors, Chris LaCivita and Susie Wiles, said in a statement after Mr. Dans’s announcement. “Reports of Project 2025’s demise would be greatly welcomed and should serve as notice to anyone or any group trying to misrepresent their influence with President Trump.”

Project 2025 has not been shut down, the Heritage Project confirmed Tuesday. 

One of the most ardent advocates for the project, the Heritage Foundation’s president, Kevin Roberts, sang the praises of Mr. Dans and the organization on Tuesday, saying it is a “tool” that was “built for any future administration to use.”

Mr. Roberts himself is close with Mr. Vance, interviewing him several times and describing him as the ideal candidate for vice president. Mr. Vance went so far as to write the forward to Mr. Roberts’s upcoming book, further cementing Democrats’ argument that the Project 2025 agenda and the Trump campaign have more in common than they’re letting on. 

The book, “Dawn’s Early Light: Taking Back Washington to Save America,” details a Project 2025-esque plan that “identifies institutions that conservatives need to build, others that we need to take back, and more still that are too corrupt to save.”

In the foreword, Mr. Vance describes Mr. Roberts’s policy platform as an “essential weapon” for the conservative movement and the next GOP administration, adding that it was time to “circle the wagons and load the muskets.”