Spurs captain Romero facing increased ban after Liverpool red card
The Tottenham Hotspur captain received a second yellow card for kicking out at Liverpool defender Ibrahima Konate before being ordered off the field by referee John Brooks during a 2-1 defeat.
Romero's dismissal left Spurs down to nine men as Xavi Simons had already been shown a red card for serious foul play in the first half.
Argentina centre-back Romero had first been booked for dissent after complaining he had been pushed by Hugo Ekitike when the forward scored Liverpool's second goal.
Romero's red card means he will serve a one-match ban, missing Sunday's match away to London rivals Crystal Palace.
But he now faces additional punishment, and a longer ban if found guilty. He has until January 2 to respond to Wednesday's charge.
Spurs travel to Brentford on New Year's Day before hosting Sunderland on January 4 and visiting Bournemouth three days later.
"It's alleged that he (Romero) acted in an improper manner by failing to promptly leave the field of play and/or behaving in a confrontational and/or aggressive manner towards the match referee after being sent off in the 93rd minute," said an FA statement.
Romero went into the game on seven bookings in the Premier League this season and Tottenham head coach Thomas Frank accused Brooks of failing in his duties by sending the defender off the field.
"There is a massive mistake by John on the pitch," said Frank.
"Two hands on the back by Ekitike. I don't understand how he didn’t see it. OK, luckily we have VAR so they will bail you out when you need it, which they didn’t. That was the second mistake."
The Danish boss added: "I think if you go back to that (second Liverpool goal) and the referee did his job, then it would not have been a first yellow (for Romero). Is that fair to say?
"I have a player that is extremely passionate, and if you have a passionate player then you need to go to the line sometimes."
Defeat left Spurs a lowly 14th in the table and added to the growing pressure on Frank, who took charge after Ange Postecoglou was sacked in June.