Reading the last tweets from president Trump, I thought "tiene cola de paja", meaning (I'll try to define the notion in my own words expanding on this event) "he knows that he has been caught telling lies and contradicting himself so he's afraid of making a blunder and be accused with a massive 'liar, liar, pants on fire' "
A person who "tiene cola de paja" is very careful about what they do, as they have vulnerabilities -a straw tale- that may caught fire on the slightest distraction.
Is there an English equivalent?