By targeting federal pensions as a culprit in the growing national debt, White House officials and congressional leaders are taking aim at a benefit lost long ago by many workers at private companies — a guaranteed retirement check paid largely by the boss.

These traditional pensions, called defined-benefit plans, have long been an attractive feature of government work. But President Obama’s bipartisan fiscal commission has described them as “out of line” with private-sector retirement packages, which rely increasingly on 401(k)-style accounts that require employees to contribute more and carry more risk.

Now, as part of a compromise to limit federal borrowing, many Democrats and Republicans want federal civil servants to do the same: Pay more into their pensions.

“The comparison is really one of, ‘Well, private-sector employees have been cutting and cutting retirement income security, and government employers haven’t,’ ’’ said Dallas L. Salisbury, president of the nonpartisan Employee Benefit Research Institute.

It’s the same argument public workers have confronted for months from critics who compare their job security and salaries with millions of private-sector workers who have lost jobs or faced pay cuts.

Today, half of private companies offer any kind of retirement plan at all. And the majority of those offer employees 401(k)-style plans, which have taken big hits in the stock market in recent years. Less than 1 in 5 workers at private companies have traditional pensions, down from half in the early 1980s, according to the Employee Benefit Research Institute.

By contrast, when they leave federal jobs, most U.S. government workers will draw from a hybrid retirement plan, a combination of a pension and 401(k)-style account. But whether they will be better off in retirement than their private-sector counterparts depends on how long they stayed in government and the salary they might have received in private industry.

“In some cases the pension may be more generous, but the pay is a lot less generous,” said Rep. Gerry E. Connolly (D-Va.), who has about 120,000 federal workers and retirees in his district and opposes the pension proposal.

With stock options and profit-sharing still offered at some companies, pensions “are one of the few incentives we have to bring people into government,” Connolly said.

The deficit commission predicts that the government could save $51 billion through 2020 by asking federal civil servants to kick in more to fund their pension plans.

A Republican plan would effectively impose a 5 percent pay cut by boosting federal employees’ contribution to 6 percent of their salary from the current 0.8 percent. Administration officials are pushing a smaller contribution hike that would be phased in gradually and exempt some workers.

“For us it’s not about the size of [government] pensions,” said David Kendall, a senior fellow at Third Way, a centrist Democratic think tank also promoting a change. “Pensions in general need to go up. The problem is the government contribution.”

Overall, Third Way calculates that the government contributes 12.7 percent of an employee’s salary to his or her retirement account — which also includes the 401(k)-style thrift savings plan— compared with 5.3 percent put in by private employers.

Still, “it’s not an extraordinarily generous plan,” Gary Burtless, a labor and public finance economist at the Brookings Institution, said of the federal system. “Not by the standards of old-fashioned pensions offered by private employers.”

Those “old-fashioned” plans are generally good deals for workers because they guarantee a certain benefit at retirement, based on years of service and salary. The employer must pay for it, even if the fund’s investments perform poorly.

It’s employees who take the risk if a 401(k)-type account loses money. The employer often matches an employee’s contribution up to a certain amount — although many companies have withdrawn matches in recent years as corporate profits fell. But these defined contribution plans also have advantages. Workers can take the money with them when they change jobs, a feature traditional pensions don’t have.

The federal government actually was one of the first major employers to move away from traditional pensions, when it restructured its retirement system in the mid-1980s to bring newly hired civil servants into the Social Security system. The old Civil Service Retirement System was left alone, but the Federal Employees Retirement System was created for those hired in 1984 and later. They get a smaller defined benefit plus Social Security and employer contributions into the 401(k)-style Thrift Savings Plan, which also was created at the same time. FERS now covers about four-fifths of the federal and postal workforce.

Those retiring under FERS received $944 per month on average in 2007, compared with the $2,587 monthly benefit of those retired under CSRS that year, according to the National Treasury Employees Union. The Social Security benefit plus employer contributions to retirement savings for FERS employees are designed to roughly make up the difference.

Around the time the federal system changed, private pensions also began to erode. New accounting rules took effect, requiring private employers to pre-fund their plans, creating big risks. Many firms abandoned defined-benefit plans, which are mostly limited now to large companies.

State and local governments also didn’t follow the federal example, swinging the pendulum the other way. Most stuck with guaranteed pensions.

“These plans are always better because they’re a stable guarantee of retirement income,” said Diane Oakley, executive director of the National Institute on Retirement Security. The average monthly benefit for state and local retirees — not including Social Security — is $2,000 a month, she said.

But these funds face huge shortfalls, the result of the economic downturn and new accounting rules passed in the mid-1990s requiring the plans to be pre-funded. Now state and local workers are in showdowns with governors and legislatures over wages, pensions and collective-bargaining rights.

Some states, including Utah and Kentucky, are turning to 401(k)-type plans that sharply limit the state’s retirement contribution for new workers and some current ones. Governors in Florida and Kansas and legislatures in several states, including Virginia, are pushing similar shifts. The push is led by Republicans, and in many states, Democratic-supported public-employee unions are resisting such drastic restructuring.

In Washington, most observers agree that the federal system is likely to change in a year in which government workers have faced a two-year pay freeze. How dramatically is unclear.