From Where I sit - Threat to national security

Throughout the history of the US, the nation has drawn strength from its large, established middle class - families who owned homes, saved for retirement and lived in relative security. They could certainly afford to send their children to college and continue the cycle of middle-class status.

Rapidly rising public tuition costs threaten this security. State support for higher education is decreasing. In response, tuition costs increase even though incomes are flat and unemployment remains high.

Parents take out loans or second mortgages when they should be saving for retirement, and students graduate with larger loans and struggle to secure their own middle-class status. The ripple effects will continue for decades.

Unaffordable higher education damages our nation and its future prosperity.

It may be surprising, but the largest burden from the high cost of tuition does not necessarily fall on the poorest students because of the availability of need-based financial aid.

It is the students who fall in between the extremes of rich and poor, the students from solid middle-class families who make too much to receive grants but too little to afford college costs, who shoulder the greatest burden.

This disproportionate impact is particularly extreme in California, an inadvertent side-effect of California's dedication to making higher education accessible to low-income students. The state's financial assistance programme, the Cal Grant, is one of the most generous state financial assistance projects in the country. These grants are given to undergraduate residents who enrol in a college, university or approved technical or career school in California, meet minimum grade-point requirements, and whose family income falls below the income ceiling ($78,100, or £49,483, for a family of four in 2011-12).

For eligible students who attend the University of California or the California State University, Cal Grants cover 100 per cent of their tuition. As a result, when tuition increases, Cal Grants cover the higher costs.

Even some students from families earning above the state's median income ($61,100 in 2010) can receive grants to cover all of their tuition. This is much more generous than the assistance available from federal grants. Virtually no students with family incomes over $60,000 receive federal grants, and since Pell Grants, the most common federal grant, are capped at $5,550 a year, they are unlikely even to cover tuition.

There is little doubt in my mind that a family with an income of $80,000 already struggles to afford the costs of attendance when the average yearly cost for an in-state student at a four-year public institution - including tuition, fees such as lab charges, room and board, books, transport and expenses - was $21,447 for 2011-12.

The proposal by California's governor, Jerry Brown, for a temporary sales-tax rise and income-tax increase on the wealthy will prevent additional funding decreases to public higher education.

However, it does not address the current unaffordability gap. We need to take the next step to address existing inequities and the struggle of middle-class students. There are no easy solutions, but there are serious consequences if we allow higher education costs to continue to spiral beyond the reach of the middle class.