In the days since Joe Biden’s disastrous debate performance, a sizable chunk of the liberal commentariat has called for the sitting president to drop out of the race. The Biden campaign, meanwhile, says the 81-year-old is not going anywhere. On this point, Biden and Donald Trump agree. According to multiple sources, Trump expects that—barring a health crisis—the historic effort to dump Biden will fail. “They’re stuck with Biden,” a senior Trump campaign source told me. Longtime Trump confidant Kellyanne Conway agreed, arguing that Democrats are too disorganized to draft a replacement. “That party has fallen into a state of sclerosis,” she said.

Some Republicans outside the Trump campaign, however, worry that Democrats will find a way to jettison Biden for a more competitive candidate. Over the weekend, Trump’s primary rival Nikki Haley told The Wall Street Journal that the ex-president needs to prepare to face a younger opponent. Sources I spoke to said that would be a worst-case scenario for Trump. “We need to make sure Biden stays on the ballot and there’s no bait and switch,” a veteran of Trump’s 2020 campaign said. Another MAGA-world insider said Trump potentially walked into a trap by agreeing to debate Biden before the party conventions, leaving Democrats with enough time to make a change. According to this source, the party won’t let Biden remain on the ticket. “They will force him out because they don’t intend to lose,” the source said.

These Republicans speculate that Democrats will tap a popular centrist governor to be the nominee. Names I heard floated include Pennsylvania’s Josh Shapiro, Michigan’s Gretchen Whitmer, and New Jersey’s Phil Murphy. The 2020 Trump campaign veteran, however, thinks Vice President Kamala Harris is the only realistic replacement for Biden. “They can’t sidestep her,” he said.

For months, the Trump campaign has pushed a narrative that Biden is too senile to be president, but senior Trump adviser Jason Miller told me the GOP candidate expected Biden to be stronger after his week of preparation at Camp David. In the end, two sources said, the candidate himself was taken aback by how frail and incoherent Biden seemed to be. “He felt sad for America and then got upset,” said the 2020 campaign veteran, who was briefed on conversations Trump had after the debate.