A fair debate over university admissions policy is impossible due to the "toxic" political arguments surrounding the issue, according to the president-elect of Universities UK.
Steve Smith, vice-chancellor of the University of Exeter, said politicians blame universities for unwelcome social mobility figures even though the class bias in attainment levels is driven by many students' failure to achieve five good GCSEs at the age of 16 - something universities can do little about.
He added that MPs also wrongly conflated widening participation in higher education with concerns about ensuring access to top universities for state-school students.
In London last week at a Universities and Colleges Admissions Service conference on modernising admissions, Professor Smith said: "The data on social mobility is very stubborn. Ministers look at (it) ... and ... blame someone. Universities are seen as the organisations that help propagate ... patterns of fixed social mobility.
"The key to social mobility is getting people through at 16, not the bias of university admissions. When ministers are talking about widening participation, they're thinking about fair access to (Oxbridge)."
Fair access to top universities affects 3,000 high-achieving state- school pupils a year, he explained, whereas widening participation affects the 360,000 16-year-olds who fail to achieve five good GCSEs.
"Isn't that rather more important? That explains the toxic nature of the debate," Professor Smith said. "It's political in all sorts of ways," he said, citing poor media understanding of the admissions process and politicians' outdated views.
The Conservatives could exacerbate the problem, he suggested. "A (David) Cameron Government will almost certainly ... allow the most popular universities to expand."