Leading European allies are undermining negotiations to oust Venezuelan strongman Nicolás Maduro because of their hesitance to impose sanctions on the regime, according to a top U.S. official.

“Many of the Europeans are making a real mistake here, because many of them take the position, while these negotiations are ongoing, we shouldn’t do sanctions,” Elliott Abrams, the State Department’s special representative for the Venezuela crisis, said Wednesday. “And this is exactly wrong, because while they are ongoing, if you want them to succeed, you need to increase the pressure on the regime to compromise.”