You really don't understand what's going on, do you?
Republicans have been selling their base a narrative that the southern border is an existential crisis to our nation, but now when presented with a bill that effectively gives them everything they've demanded, they're refusing to act because doing so would take away their only real campaign issue.
You don't wait until some indeterminate time in the future to address existential threats - so the GOP has been exposed as the ridiculous fearmongers we've always known they were.