Our nation's aging baby boomer population is increasingly anxious about the long-term health of our federal entitlement programs. While doomsday predictions abound for the impending insolvency of both traditional Medicare and Social Security, there is one portion of Medicare that is saving money and out-performing all expectations: Medicare Part D.

Last weekend marked the 10th anniversary of Part D, a prescription drug benefit program for seniors that exemplifies what is possible when government fosters competition in the health care marketplace instead of pursing a one-size-fits-all approach.

The goal of the program was to lower costs and increase access to prescription drug coverage for low- and moderate-income seniors. The program allows the free market to work and forces companies to work hard for customers by delivering a high-quality, affordable product. Beneficiaries are able to choose between multiple private insurance plans, offering different levels of coverage, impacting an individual's benefits and costs. This structure has made it possible for the cost of Part D to come in under all estimates. The average monthly premium is approximately $30 for enrolled seniors -- nearly half of the 2004 predictions. And for the federal government, the cost of the program is predicted to decrease by billions of dollars.

Since its launch, Part D has become wildly popular among our nation’s seniors. Enrollment has grown nearly 150 percent and enabled millions who did not previously have prescription drug coverage access to the medicines they need. A recent KRC Research survey showed that nine out of 10 seniors are pleased with Part D, and nearly as many said their drug costs would be higher without it. The survey also shows that without Part D, 67 percent of seniors say they would be unable to fill their monthly prescriptions.

Part D has been so effective the program is helping reduce expenditures in other parts of Medicare. According to Harvard researchers, it has played a significant role in providing seniors with better prevention and health care management tools, cutting down on annual hospital visits by 77,000 and saving taxpayers billions.

Now compare the success of Part D to the president's health care law. The Affordable Care Act shares the same laudable goals as Part D -- increased access and lower costs -- but fails to leverage market forces and competition. Instead, the president's health reform puts a top-down, government-run program in place to control costs through cuts and limitations.

The government’s effort to contain costs in the ACA comes at the expense of quality and choice for patients. When the government decides pricing for a program like Medicare, doctors and providers feel the strain of decreased reimbursement rates that fail to cover the cost of the services. If the size of the government’s contribution continues to decrease, taking on more Medicare patients becomes prohibitive for many doctors, forcing them to scale back involvement or leave Medicare entirely. Seniors are left with fewer choices when seeking doctors who accept Medicare and this decrease in competition and choice brings down the quality of care.

Put simply, for those seniors who rely on Medicare for their care, the health care law is a bad deal.

It doesn't have to be this way. We know from Part D's success that market competition in health care and entitlements can work for beneficiaries. Instead of setting prices, the government can work with industry leaders to set rigorous standards that fulfill the promise of increased access and decreased costs. When it comes to health care policy, we should look to 10 years of Medicare Part D success as a roadmap for not only strengthening and protecting Medicare for our nation’s seniors, but improving the health care system for all Americans.

Rep. Peter Roskam, R-Ill., is chief deputy Republican whip in the House.