California state Sen. Scott Wiener, a Democrat from San Francisco, is reportedly running for the seat former House Speaker Nancy Pelosi (D-Calif.) has held on to for nearly 40 years, resisting calls for her to step aside and usher in the next generation of lawmakers.Wiener, 55, whose planned campaign was reported Friday by The New York Times and The San Francisco Standard, isn’t Pelosi’s first primary challenger, but he’s perhaps her most serious one yet.A former San Francisco supervisor who’s represented the city and part of a neighboring county in the California State Senate since 2017, Wiener has built a big profile successfully pushing for more housing development, protections for transgender Americans and a requirement that presidential candidates disclose their tax returns to appear on California’s ballot in 2020. (President Donald Trump sued him for that one, and the courts ultimately struck down the policy.)Rep. Nancy Pelosi (D-Calif.) after a rally with members of the Democratic caucus on Sept. 30.Tom Williams via Getty ImagesBut even with his acclaim, Wiener should expect to face “a decidedly uphill battle” if Pelosi runs again, California Democratic strategist Steven Maviglio told HuffPost on Friday.“Few will want to cross her by endorsing her opponent or making contributions,” Maviglio said. “Wiener is an appealing candidate with a solid legislative record. But defeating Pelosi, the patriarch of SF politics and a national hero to many Democrats, is a tall order, particularly in a Top 2 election.”Though Pelosi, 85, has filed candidacy paperwork to run again in 2026, she hasn’t formally announced her plans. She has never competed in a close race, save for the special election when she first ran for the seat in 1987.Wiener, who also filed that paperwork over the summer, hasn’t kept his aspirations for Pelosi’s seat a secret, but he previously indicated he’d wait until she stepped aside to launch a campaign.State Sen. Scott Wiener at a Halloween event while campaigning in San Francisco last October.via Associated Press“I’ve been clear that I intend to run for this seat whenever the race opens up, whether in 2026 or 2028,” Wiener said in a statement when he filed the paperwork.Wiener’s office did not respond when asked to comment on the reports, but sources familiar with the plans told the Standard an announcement from him is expected next week. When reached for comment, he told the outlet: “I’ve been preparing and raising money for whenever the race starts.”Though she stepped down as House speaker in 2022, Pelosi is regarded as one of the most powerful women in politics. She regularly spars with Trump and reportedly played a critical role in pressuring former President Joe Biden to exit the race last year, clearing the way for then-Vice President Kamala Harris’ ultimately unsuccessful campaign.“I’m doubtful the appeal of generational change is enough to dislodge her.”- California Democratic strategist Steven MaviglioThe biggest threat to Pelosi’s legacy may be her refusal to step down. Polling by Beacon Research for Saikat Chakrabarti, who’s running for Pelosi’s seat after serving as Rep. Alexandria Ocasio-Cortez’s (D-N.Y.) chief of staff, found that 51% of people had supported Pelosi in the past but “now think it’s time for a change.”But Maviglio is skeptical that interest in new faces will be sufficient to oust Pelosi.“I’m doubtful the appeal of generational change is enough to dislodge her,” he said, adding that he expects Wiener will focus on this in his campaign. “If it were an open seat,” he said, “it would be an entirely different story.”