Consider this: Roughly half of American workers today don't have a retirement plan through their jobs. That's roughly 75 million people who, if they don't save enough on their own, will end up with little more than Social Security to support them in their old age. Many work for small businesses whose owners argue that 401(k)s and other government-approved retirement plans are too complicated and expensive for them.

Now, though, an idea is gaining attention on Capitol Hill that would offer this "other half" of the work force a convenient way to save for old age. It's called the automatic IRA, or auto-IRA for short, because it would enroll workers in individual retirement accounts funded through automatic payroll deductions. Workers could "opt out," that is, specifically decline to participate.

"This is a modest proposal that has the promise and the possibility of making a big difference," says Sen. Jeff Bingaman, D-N.M., who along with Sen. Gordon H. Smith, R-Ore., is cosponsoring auto-IRA legislation in the Senate. "It doesn't try to change the world, but it does try to begin to provide more of an opportunity for retirement savings for these 75 million or so Americans."

In the House, Reps. Richard E. Neal, D-Mass., and Phil English, R-Pa., are cosponsors. The plan was designed by David C. John, of the conservative Heritage Foundation, and J. Mark Iwry, of the liberal-leaning Brookings Institution. "Some issues go past ideology, past party loyalty," John says of the bipartisan support.

The auto-IRA harnesses the power of inertia, proponents say. One recent study of 401(k)s—the employer-sponsored retirement plans—showed that when enrollment was made automatic, participation by newly hired workers leaped from 24 percent to 86 percent. Supporters also say that the auto-IRA legislation would affect the small business market, which has historically resisted offering retirement plans. Once workers see what systematic saving can do, they might press for other plans that would allow an employer match.

At this point, however, small businesses are not racing to embrace the auto-IRA proposal, especially the requirement that businesses provide auto-IRAs unless they offer another type of retirement program.

"We are philosophically opposed to government mandates. Our members want the flexibility to offer their employees what [the employees] want," said Mike Diegel, spokesman for the Washington-based National Federation of Independent Business. And recent polling of NFIB members showed that health insurance is the preferred benefit, he said.

Still, once employees try them, auto-IRAs could build their own fan clubs. Take, for example, Pierre Randolph, a building engineer in his mid-40s at an apartment complex in Washington. His employer is a small management firm that took the unusual step of helping its workers set up IRAs.

Randolph, who's been working for 21 years, said he has more than $20,000 saved up. A lot of people have stayed with the company because of its IRA program, he says. "This is very important to people like me."

Albert B. Crenshaw wrote for The Washington Post for 24 years.