Union workers protest at the Greater Boston Tea Party's third annual "Tax Day" rally on Boston Common in Boston, Friday, April 15, 2011. (AP Photo/Winslow Townson)AP

President Obama wants his presidency to be about big things. He sees himself as a transformative leader. To that end, in his first term he overhauled the nation's health care, rewrote the rules for the financial system, and installed a consumer watchdog. But if he wants these big things to survive, he will need to spend his second term focused on what may seem to be the little things.

Presidencies are often judged by a legislative scorecard toting up the number of laws pushed through Congress. A different metric may be needed, though, for Obama's second term, one that assesses how skillfully he implemented the laws passed in his first term. Did he make them do what they were supposed to do? Did he persuade a skeptical public that the changes worked for them?

The reality (not totally accepted by the White House) is that nothing achieved through those first-term triumphs is guaranteed to survive the next decade and the next president. In part, that is because Republican opposition is so implacable and so determined, in a way not seen in the past. And, in part, that is because a president renowned for his oratory has done a poor job of persuading the country that it needs to preserve these accomplishments. There is no better example than the centerpiece of Obama's legacy, the Affordable Care Act, which remains deeply controversial and threatened even as it approaches its third anniversary.

Exit polls conducted for CNN in November showed support for at least partial repeal of the health care law by 55 percent of voters in Colorado, 53 percent in Iowa, 52 percent in Ohio, 50 percent in New Hampshire, and 49 percent in both Florida and Illinois — all states the president carried in November. A Rasmussen Reports survey on Jan. 25-26 found that 51 percent of the 1,000 likely voters polled view the law unfavorably and 45 percent view it favorably. And this is before the real implementation begins with the all-but-certain flood of stories about problems related to enrollment, costs, and eligibility.

George Schultz, President Reagan's secretary of State, once famously said, "Nothing ever gets settled in this town. It's a seething debating society in which the debate never stops, in which people never give up." That certainly applies to a law so far-reaching and contentious. All laws have unintended consequences that require Congress to pass fixes. Bills have been introduced in every Congress since 1935 to tweak Social Security and in every Congress since 1965 to change Medicare. And neither program is as complicated as "Obamacare."

"On complex pieces of legislation, you don't get them right the first time through," says former Rep. Lee Hamilton of Indiana, who is director of the Center on Congress at Indiana University. "Getting those things right is very, very hard to do. Nobody could expect to do it the first time through. You need to tweak them, amend them over a period of years. Circumstances change. Budgetary considerations change. Demographics change. So there are many things that impact these sweeping pieces of legislation."

Stephen Hess, a former aide to Presidents Eisenhower and Nixon who is now at the Brookings Institution, sees the Affordable Care Act as "a rough, awkward piece of legislation with lots of loose ends" that will be challenging to implement.

The challenge is heightened by the president's first-term decision to push it through with only Democratic votes. In doing so, he recognized that Republicans — particularly in the House — were determined to oppose him. But he also was rejecting the lessons of Social Security and Medicare. Presidents Roosevelt and Johnson understood that major social changes endure only when they have bipartisan support. Both gave up much of what they wanted to secure Republican votes. Social Security passed with 15 Republican votes in the House and with 16 Republican votes in the Senate to only five "nays" in that chamber. In 1965, 68 House Republicans and 17 of the 30 Republicans in the Senate voted for Medicare. In contrast, the Affordable Care Act had no Republican support in either chamber.

Bipartisanship has a carryover effect when it comes to implementing a law. Republicans were invested in making Social Security and Medicare work. No Republican platform ever called for the outright repeal of either one. GOP leaders understood the programs' popularity. In contrast, the Republican platform in 2012 condemned Obamacare nine times, repeatedly demanding its repeal. Again, GOP leaders were reading the polls. And when the administration goes to Congress with needed fixes, it will meet resistance from Republicans who would rather see the flawed law fail.

Obama did not use his 2012 campaign to rally the public behind the health care law. He gave one speech in which he effectively outlined its benefits, speaking on Aug. 29 in Charlottesville, Va. But then he seemed to believe the issue was settled. "The law is here to stay," he said. "The Supreme Court has spoken. We're not going to refight the battles of the last four years."

But those battles are not over. "His legacy will be determined by how he protects his major pieces of legislation over the next four years," contends James Thurber, director of the Center for Congressional and Presidential Studies at American University. "It will be politics through different means, not building coalitions on the Hill and passing new big bills."¦ It will be small, little things that happen in the executive branch and small, little things on the Hill."

How well the administration does those little things, and how well the president changes public opinion, will determine whether history sees him as a president who did big things that endure.

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