Two Liberal Democrat councillors have switched allegiances to become the first Conservatives on Oxford City Council for five years.
The pair are the first Tory councillors in Oxford since 2002
Councillors Tia MacGregor, Quarry and Risinghurst, and Paul Sargent, Carfax, officially switched parties to the Conservatives on Friday.
Their former colleagues have said they should resign their seats.
Conservative leader MP David Cameron said they would be an important presence for the Tories in Oxford.
Told to resign
Mr Cameron said: "I'm looking forward to the election. I think it will help hugely to have two representatives in the city if Oxford.
"The most important thing, sometimes, to build yourself back into a city is to have representatives on the ground."
Former colleagues of the two councillors have said they should resign and hold a by-election.
In response, Mr Sargent said: "Firstly, there's less than a year of my current tenure left. Secondly, in my ward, seventy-five percent of the electorate are students.
"They are now leaving Oxford at the end of their term, so you would have seventy-five percent of the electorate disenfranchised from a vote."
Ms MacGregor, said: "There are going to be people in my ward who are unhappy.
There are going to be people in my ward who are deeply unhappy with what I've chosen to do. I can't deny that."
But one resident asked how she felt about the defection, reflected an altogether different view.
"To be honest, I think that there's not much of a difference between the parties at the moment. I really don't think it is much of a shift," she said.