The Conservative party, led by David Cameron, won Thursday's UK general election, securing an absolute majority of 331 seats in the British parliament. Cameron has pledged to hold a referendum on Britain's membership in the European Union by 2017.
"I think it's clear that the referendum about our continued membership in the European Union is very much on the agenda… So I think it gives us another two years of very difficult relations. And within the European Union as a whole," Jean Lambert said.
"And I don't think that two years is necessarily long enough for David Cameron to get sort of change that he has been talking about," Lambert concluded.
Earlier on Friday, congratulating Cameron on his re-appointment, President of the European Council Donald Tusk said he relies on the prime minister to continue the country's membership in the European Union.