Robert Jackson, a former higher education minister, has made it clear he would vote against a Bill which barred unions from using public funds for political campaigning, and his views are supported by other Conservatives.
The Government's small majority means that eight Conservative MPs could theoretically defeat the Bill. The threat is provoking speculation that the Government may quietly drop the proposed legislation to avoid further embarrassment over its education policy, particularly since it will encounter fierce opposition in the House of Lords.
Mr Patten's proposals would limit public funding of student unions to a small group of core activities, such as welfare, catering and sporting services. Unions wishing to affiliate to political organisations, including the National Union of Students, would have to persuade students to pay for it themselves.
But Mr Jackson said the proposed legislation was 'a great sledgehammer to crack a nut', and represented too serious an incursion into university autonomy. 'Universities are self-governing entities, and it is very important that they remain so.'
He said those who supported the Bill objected to individual students being made to do things against their will. 'But in a case like this it is not only the freedom of the individual that needs to be considered, but the freedom of the association.'
The consultation period for the legislation has been extended by one month to the beginning of November, giving universities time to respond once term starts.
A spokesman at the Department for Education denied there were plans to drop the legislation, but suggested it might be possible to implement some student union reform without the need for primary legislation.Reuse content