"Sadly, what we see from the Labour Party (is) their various attempts to frustrate Brexit and frustrate this vote," May told the BBC.
"What I see from Labour is an attempt to frustrate what the government is doing to deliver Brexit for the British people," May said. "That is actually a betrayal of the British people."
When asked by ITV what her Plan B might be if her deal is defeated in parliament, May said: "I'm proposing a deal, I'm proposing a Brexit with a good deal for the UK."
(With inputs from agencies.)