Trump said that if Biden doesn't complete the border wall, the public would revolt. A preponderance of the evidence shows that Trump's wall is low on the public agenda with most not in favor of it. Congress, including the Republicans, was clearly not in favor of it. Trump failed at convincing Congress to appropriate money for it, which is why Trump had to resort to declaring a (fake) national emergecy and repurpose military money to pay for it. A federal appeals court has ruled that his repurposing is illegal. It's another instance of Trump not being in touch with reality and worried that his monument wall might not be completed if he isn't reelected.