More than a dozen Republican senators want to end defined benefit pensions for federal employees, leaving in place only the Thrift Savings Plan and Social Security.

Sens. Richard Burr (R-N.C.) and Tom Coburn (R-Okla.) introduced a bill last week to cut the benefit. It has since drawn 11 additional co-sponsors, including Sen. John McCain (R-Ariz.) and several other members of the Homeland Security and Governmental Affairs Committee.

The bill would not affect current federal employees. Instead, the pension would be cut from the Federal Employee Retirement System starting with 2013 hires. It would also apply to members of Congress.

"Right now, federal government workers receive far more generous retirement benefits than private sector employees. The cost to taxpayers of these benefits is unsustainable and we simply cannot afford it," Burr said in a statement. "We cannot ask taxpayers to continue to foot the bill for public employee benefits that are far more generous than their own."

The bill comes little more than a week after a House Oversight and Governmental Reform subcommittee held a hearing on whether federal employees are overpaid. Andrew Biggs, a resident scholar at the conservative American Enterprise Institute, testified that government workers enjoy much better benefits than their private-sector counterparts. Chief among those benefits is the defined benefit pension, which guarantees a certain payout upon retirement.

After the hearing, Rep. Dennis Ross (R-Fla.) -- chairman of the Federal Workforce, U.S. Postal Service and Labor Policy Subcommittee -- said he might introduce legislation to address what he considers an overgenerous pay system. He mentioned a less extreme possibility than Burr's solution: Basing retirement on employee's top five years of federal pay, rather than the current three.

Union leaders say federal employees are compensated fairly -- especially considering the Bureau of Labor Statistics' finding that public-sector employees earn as much as 24 percent less than their private-sector counterparts. Office of Personnel Management Director John Berry has also called government compensation "competitive."

But in a press release, Burr said the defined benefit pension goes far above what is offered in the private sector, where employers often only offer matching contributions to a 401(k) plan. The Federal Employment Retirement Plan, he said, is underfunded by almost $1 billion.

The current plan, Coburn added, "only serves to foster political careerism."

"When American families across the country are being asked to sacrifice in order to meet their basic needs, federal employees and members of Congress should not be the exception," Coburn said in the release. "Defined benefit pension plans are going belly-up across the nation because politicians and employers continue to make promises they cannot keep."

Click here to read Burr's bill.