BLACKBURN MP and Foreign Secretary Jack Straw is being tipped at Westminster to take over as Deputy Prime Minister if John Prescott is forced to quit over his affair with his Diary Secretary.

And some observers even see Mr Straw as a leadership candidate if the PM is forced out of office by the latest rash of problems surrounding the government.

With Tony Blair expected to reshuffle his Cabinet after Thurday's local elections, minds in Westminster are turning to who will get what job.

Home Secretary Charles Clarke is also on notice from the Premier that unless he works fast to sort out the fiasco over overseas prisoners his job is under threat.

Health Secretary Patricia Hewitt and Education Secretary Ruth Kelly could also face the axe if Mr Blair opts for a major reshuffle.

Mr Straw said: "There is currently no vacancy for either Prime Minister or Deputy Prime Minister. The question of their future does not arise.

"Tony Blair is the best Prime Minister Labour has had. We need to get behind him.'' But others are not so sure. One senior minister told the Lancashire Evening Telegraph: "I can see Jack as Deputy Prime Minister if Prescott goes. It's definitely a possibility."

Mr Straw said of Mr Prescott's current difficulties: "He has done a good job as Deputy Prime Minister and deputy leader."