Generation, perhaps more than income, may be the context that most defines Americans in the perplexingly angry debate over health care reform. If needed changes are to win congressional approval, this age divide should get close attention.

As a start, the administration would do well to use the younger generation for a pilot program for expanding publicly funded health care systems beyond Medicare, Medicaid and Veterans Affairs.

Writing in the Aug. 30 issue of the New York Times Magazine, Matt Bai notes a recent poll revealed that 57 percent of voters under the age of 50 favor the outlines of the Democratic plan. That’s a full 5 percent more than voted for the president. But when those over the age of 65 were asked the same question, just 37 percent favored the proposal.

Those numbers inspire proponents of health care reform to scratch their heads in dismay. After all, almost all people over 65 enjoy the benefits of Medicare, the successful and passionately embraced government-run health care plan. Mr. Bai offers an explanation.

“Successful Democratic candidates have long relied on oldsters who grew up worshipping Franklin Roosevelt and who cherished their Medicare and Social Security,” he wrote. In fact, Democrats have made electoral hay for decades by suggesting Republicans plot “to strip seniors of their pills and pensions.” Now, Mr. Bai writes, it’s Democrats who want to find savings in Medicare while Republicans “are the ones expertly exploiting fear among the elderly.”

How did this switch happen?

Though Democrats enjoyed a 12-point advantage among seniors in the last election, Mr. Obama earned just a third of them as voters. Some conjecture that these seniors, who came of age in a segregated America, may have had a hard time accepting an African-American president. But the notion of a president born after 1960 also may be difficult for them to embrace. Mr. Obama’s campaign included “implicit indictments of the past,” which may seem to be pushing seniors “not so gently toward the inevitable exit,” Mr. Bai writes.

Also, we may incorrectly see seniors as those most familiar with the successes of the New Deal. A 70-year-old, Mr. Bai notes, would have been born in 1939, and so “has no personal memory of FDR, but he would have lived through the pain of disappearing manufacturing jobs and family farms, and the rapid deterioration of urban neighborhoods and schools, conditions unabated by government experiments in welfare and public housing.”

Ronald Reagan was president during this demographic’s prime earning years, he notes, and so “these voters may not be nearly as sympathetic to Obama’s vision of an activist government as Democrats might have assumed.”

To get meaningful reform of health care, which is critical to the economy, the administration should assure seniors that Medicare will remain. It also should consider a public option plan, like Medicare, for those born after Woodstock, who would characterize it not as socialism or an attack on the Constitution, but rather a bargain.