Once a government is perceived to be in trouble - even one with the protection of a landslide majority - every contentious issue is billed as the one that could bring it down. First it was Iraq, then foundation hospitals and, for the rest of the summer at least, it will be top-up fees.
Parliamentary arithmetic says ministers should have their way in the end, but good judges on the Labour benches and - privately - even some whips, think this time might be different.
There are good reasons to believe that government loyalists are not simply trying to frighten potential rebels back into the fold. For many Labour backbenchers, not only would top-up fees represent a betrayal of poor families, but the manifesto on which they won their seats also provides moral ammunition for resistance. Its promises may not cover the next parliament, but the MPs see early legislation as breaching the spirit of their compact with the electorate. Some gave their constituency parties a commitment to oppose any such bill in recent reselection interviews. Nor can ministers rely on opposition votes: although a minority of Conservatives see their party's populist higher education policy as irresponsible, they will not want to save the government from defeat.
Philip Cowley is surely right to predict concessions on fees (page 16), but the changes required to win over the doubters may render the eventual scheme uneconomic. There are already doubts about the sums this will raise for universities that pour a substantial share of fee income into bursaries. Extensive modelling will need to be done this summer to strike a workable balance. The question for MPs who value higher education must be whether there is a realistic alternative to increasing fees. To pretend that salvation could lie with higher taxes is to be no more honest with the electorate than to sail close to the wind on the manifesto. Economic conditions rule out across-the-board rises in public spending, and universities were not even mentioned in the prime minister's summer review of public services. The probable alternative to higher fee income is a continuing squeeze on funding levels and eventual contraction of the system, as ministers pursue their priority of preserving international competitiveness.