It’s been 131 days since Donald Trump bragged that he killed Elizabeth Warren’s presidential campaign by mocking her claim to Cherokee ancestry, but her candidacy is more alive than ever. The Democratic senator tripled her fundraising haul last quarter, is commanding massive crowds, crushing the debates, and has settled into a comfortable third place in primary state polling, putting pressure on Bernie Sanders. The “Pocahontas” slur, Republican insiders fear, isn’t cutting it.

Several strategists tell the Daily Beast that Trump was caught off guard by the resonance of Warren’s populist rhetoric—a skill set that in some ways mirrors his own, minus the mental effluvia and human rights violations—and said she might be “tougher” to compete against than he realized, repeatedly asking advisers whether they consider Warren to be a “fighter.” Others confessed that, despite their best efforts to comb her record for dirt and to workshop attacks, the GOP oppo machine has been struggling to land any blows. Sure, some of Warren’s proposals are pie-in-the-sky, and maybe the math is hazy, but have you listened to Donald Trump? One strategist suggested that conservative think tanks have been struggling to keep up with the sheer volume of white papers Warren has been generating.

It doesn’t help that anti-Warren stories haven’t gotten as much pickup in the media, mainstream or otherwise. “We all push out the bad Warren stories but they don’t go very far,” the source said—a point echoed by nearly a dozen others. “Sure the Republican base will ultimately loathe Warren, but she doesn’t inspire the same kind of historic vitriol that Hillary Clinton did,” one of the strategists told the Beast. “That, combined with fact that SCOTUS isn’t on the line as it was in ’16, and remembering that Trump needed the perfect inside straight to barely win last time, and any Democrat is going to be tough to beat, Warren included.”