The pressure is mounting on Norwich MP Simon Wright after the National Union of Students set their sights on triggering a by-election to oust him because of the Liberal Democrat U-turn on tuition fees.

But the Lib Dem MP for Norwich South insisted he had yet to make up his mind on how he would vote on changes to tuition fees – and said he would base his decision on the evidence and not be swayed by campaigners.

The union has put Mr Wright, pictured, on a hit list of vulnerable MPs, accusing him of campaigning hard on opposing tuition fees in the run-up to the general election – at a time when his party was already considering dropping its opposition.

And they are planning to make life as uncomfortable as possible for Mr Wright, who took the Norwich South seat in May by just 310 votes from former education secretary Charles Clarke.

The NUS yesterday targeted Mr Wright through its Right to Recall campaign, hoping to make use of planned legislation which would mean MPs found guilty of wrongdoing would be vulnerable to a constituency petition which would trigger an immediate by-election if 10pc of the electorate want it.

While that legislation has yet to be introduced and it is unclear whether it would be enforceable for a perceived broken promise, the NUS is hoping it can be used to oust Mr Wright.

But Mr Wright, who signed a National Union of Students (NUS) pledge to oppose fees before the election and is still paying off his own student debt, said: 'I still haven't made a decision on how to vote because it is terribly important to look at the evidence on both sides.

'It is not as straight-forward as voting on an increase or not. There is a whole package of proposals. I know there is uncertainty that increases in fees will have an impact on people's ability to go on to higher education and I need to look at the evidence.'

Business secretary Vince Cable has outlined plans to raise the cap on tuition fees up to �9,000, with the Lib Dems arguing their pre-election pledge had not taken account of the scale of the financial problems.

Some Lib Dems have already said they will oppose the government's proposal to increase annual fees, but Mr Wright refused to follows suit.

The NUS plans to petition people in Norwich over whether they want Mr Wright to be subject to recall.

Aaron Porter, NUS president said: 'Simon Wright won his seat because he made a pledge to vote against higher tuition fees. He will lose his seat if he votes for them.'

Meanwhile, two leading opponents of the government's plans for higher education will be at the University of East Anglia tonight for a debate on tuition fees.

Adrian Ramsay, deputy leader of the Green Party, who finished fourth in the Norwich South election and might fancy his chances if a by-election was triggered, will speak at the meeting alongside former Norwich North Labour MP Ian Gibson,

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