There is, to be sure, a shelf of books by Karl Marx and his devotees, but there are also plenty of books by less radical theorists.

So why do conservative pundits such as Rush Limbaugh and editorial writers at The Wall Street Journal vilify this disarming academic economist, whom US News & World Report financial columnist James Pethokoukis labeled "the most dangerous woman in America"?

The short answer is that Ghilarducci, the 51-year-old author of When I'm 64: The Plot Against Pensions and The Plan to Save Them (Princeton University Press, 2008), is a vocal opponent of the 401(k) concept, which she charges has been a "failure at providing a secure retirement" to Americans.

Her much-publicized criticisms of 401(k) plans, and her argument that a mandatory government-supervised plan should replace them, have irked not only members of the vast multitrillion-dollar 401(k) industry, but also many rank-and-file plan participants who don't trust big government.

But in an interview at her office on Fifth Avenue in Manhattan, Ghilarducci, who directs the New School's Schwartz Center for Economic Policy Analysis, seems quite reasonable. Her credentials-she's recently been a Wurf Fellow in the Labor and Worklife Program at Harvard Law School and taught economics for 25 years at Notre Dame-put her on par with the best retirement experts in academia.

And the fact that baby boomers had seen their 401(k) plans lose several trillion dollars in the previous two months only seem to add weight to her arguments.

"The 401(k) system began as a supplemental perk for top managers," Ghilarducci said over a lunch of vegetarian sushi eaten at her desk. "It was only offered to employees initially because the Internal Revenue Service (IRS) came in and said for employers to get a tax exemption for their contributions to a plan, they had to offer it to all employees."

Over time, she said, this led to a widespread use of 401(k) plans, which often replaced older defined benefit plans. But as defined contribution plans emerged as the primary workplace savings vehicle, Ghilarducci said, it became clear to her that the system had serious shortcomings.

"Only half of employers offer 401(k) plans," she said, "and at those places that offer the plans, only half of the employees participate." Worse yet, she said, employees at the lower end of the pay scale are the ones least likely to invest in a 401(k).

But Ghilarducci's critique of the 401(k) concept goes even further. She argues that the plans aren't even good for people who do use them. "These plans do not deliver for employees because of a number of inherent flaws," she said. "One, they are voluntary, so many people don't participate. Two, many employers-and their numbers are growing-don't offer any matching contributions. Three, the fees paid to fund managers end up eroding 20% to 30% of assets over time."

Her second point, is already in evidence: FedEx and a number of other big employers recently announced that they would suspend their matching contributions because of the current recession.

Finally, Ghilarducci said, the government keeps adding more exceptions that allow people to borrow against or withdraw funds from their retirement savings, with fully half of these people tapping their nest eggs before they quit working.

Ghilarducci's proposed alternative, which really alarms her critics, and which she recommended last October to the House Committee on Education and Labor, is a mandatory "guaranteed retirement account," to which all employees and employers would contribute 5% of income (up to the Federal Insurance Contribution Act limit) each year.

Unlike a 401(k) plan, this fund would be administered by a government-appointed board of trustees. And unlike contributions to the Social Security Trust Fund, the assets would remain separately in the ownership of each worker, and could be invested in assets other than Treasury securities.

The government, for its part, would guarantee every account an annual return of at least 3% over inflation.

Most controversial of all, Ghilarducci proposes replacing the tax deductibility of 401(k) contributions, which she calls "a $110 billion subsidy primarily for the wealthy," with a $600-per-person refundable tax credit, to be invested in each citizen's retirement fund.

A political nonstarter

Not surprisingly, the fund management industry, which reaps billions of dollars in fees from 401(k) accounts each year, takes exception to Ghilarducci's attacks and opposes her call for a government-run alternative.

In a recent speech at the National Press Club, Paul Schott Stevens, president of the Investment Company Institute (ICI), the mutual fund industry trade group acknowledged that an ICI survey had found 32% of people favoring a government-run investment program. But most people, including 76% of those with retirement savings of under $50,000, favor the status quo.