text:  Live from NPR News, I'm Dale Willman. President Joe Biden's shaky performance in Thursday's presidential debate has led to calls that he drop out of the race. NPR's Domenico Montanaro says it's unlikely that Biden will drop out, but if he did, it's a potentially complicated process to replace him. The Democratic National Convention isn't until August. If he dropped out now or before the convention, which again, not likely at all,