David Ward will join a growing Liberal Democrat revolt aimed at bringing back the 50p tax rate for the super-rich.

The Bradford East MP will try to force Nick Clegg into a pledge to restore the top rate – controversially cut to 45p, last April – at the party’s conference, next month. The Lib Dem Federal Policy Committee has defied its leader by insisting on a vote, which would hit those earning more than £150,000 a year.

Members will choose between two options – keeping the 45p rate, or returning to 50p if a review found this would raise more revenue for the Treasury.

Unlike the Conservatives and Labour, votes at Liberal Democrat conferences determine party policy. Mr Ward said: “I think this is a good idea. The economics of it, in terms of whether it brings in huge amounts of money, are not conclusive – but it’s about sending out a message that we are all in this together.

“It was politically inept to abolish it right at the time when so many other people are really struggling.

“It allows Labour to say, over and over and over again, that its policies would be funded from that 50p tax rate. That’s why it was inept.”

However, the vote could create further friction with Mr Clegg, after he suspended Mr Ward from the parliamentary party because of his comments about Israel.