Philippe Lamberts co-chairs the Greens group in the European Parliament | Mathieu Cugnot/EPA Theresa May’s ‘out of her depth,’ says senior MEP Green lawmaker says British PM ‘reaching the very edge of her skills.’

British Prime Minister Theresa May is "a lady out of her depth" and "reaching the very edge of her skills," a senior member of the European Parliament said Tuesday.

Philippe Lamberts, a Belgian who co-chairs the Greens group in the Parliament, was asked about May's decision to speak to leaders of the assembly's groups rather than all MEPs.

"The impression that I get of her is that she’s a lady out of her depth, meaning that she is reaching the very edge of her skills now. And I think it’s starting to show,” Lamberts said in the Parliament.

But he added that if he were May's adviser, he'd tell her to make the same decision. "I think she had more to lose than win by coming. If she were to come to Brussels or Strasbourg I think she’d risk further weakening the U.K.’s position."

Guy Verhofstadt, the Parliament's point man on Brexit, had different advice.

"Instead of only addressing the Conference of Presidents [the group leaders] I would encourage her to address the whole house. Other heads of state have done this in the past.

"That can only be helpful because the European Parliament will need to give the green light on the negotiations."