Re: Doubling down?
"Doubling down in political context normally means that a policitian keeps on telling lies even when faced with hard facts that tell the truth / reality."
More than that. When faced with the truth, "doubling down" means not just telling the same lies but telling EVEN MORE lies: in particular attacking the source of the facts. Someone doubling down is usually a sign they actually believe them enough that they see the facts as fake.
PS. Most Americans are familiar with the casino card game Blackjack/21 which is where "doubling down" comes from.