It’s fairly rare for Americans to be united behind any particular president. Is some sense we have never been truly united politically. We certainly were not united under Abraham Lincoln. But there have been times when the nation was relatively united. The country was fairly united behind Franklin Roosevelt even before Pearl Harbor, although there were great internal debates. The country was certainly united as never before or since after Pearl Harbor.

The country was very united under Dwight Eisenhower’s leadership, despite the era of McCarthy. After the assassination of JFK, the country rallied around LBJ despite the roiling civil rights debates. Ronald Reagan enjoyed a lot of unity after his large electoral victory and his survival of an assassination attempt. What all these examples have in common is that each president came into office facing a grave crisis. FDR had the Depression, Eisenhower the Korean War, LBJ the trauma of assassination, and Reagan the Iranian Hostage Crisis, a horrid economy, and his own personal near death experience. But they also all enjoyed landslide victories.

It’s no accident that these four men were the four most successful presidents of the modern era. None of them ever faced electoral defeat (although Vietnam ruined LBJ’s chances for a second full term). What they all shared, at least for a time, was a mandate to make large changes. George H.W. Bush and Bill Clinton never had that kind of mandate. George W. Bush had a mandate from 9/11, but he squandered it in record time. All of our presidents made serious errors and misused some of the trust the American people placed in them. Some of their errors were devastating, like Vietnam and the invasion of Iraq. But the only big positive changes we have made were only possible because the president had a relatively united country and a mandate for change provided by large electoral victories.

After about 20 straight years of a deadlocked country and two straight presidential elections that were effectively ties, it is hard for us to imagine what it would be like to see a president with a basically united country and a mandate for change. But that is what we are on the cusp of achieving. You can see signs of it already in the fact that a significant number of Republicans are open-minded about an Obama presidency.

Both the Eisenhower and Nixon families are united behind Obama. Lincoln Chafee has endorsed Obama and it’s clear that Senator Chuck Hagel is leaning that way. Mike Huckabee has many nice things to say about Obama. It’s also clear that foreign policy hands from James Baker to Brent Scowcroft to Colin Powell all have more sympathy for Obama’s foreign policy instincts than for John McCain’s. Billionaires like Warren Buffet trust Obama more than McCain to run the country’s affairs.

Obama stands to come into power on the crest of a wave of young, enthusiastic voters, unprecedented non-white turnout (including Native-Americans), and near unanimous support from liberals and academia. But on top of that, he has support from Wall Street and support from the bipartisan realist school on foreign policy. Even FDR never enjoyed such a deep and wide level of support. And, while the nation is facing its problems, there are presently no issues as divisive as civil rights and Vietnam to provide easy wedges to divide the country once it is united.

But it’s up to us to make it happen. We not only need to help Obama win, but we need to help him win a landslide. And we need to help bring landslide victories in Congress, too. If we can get this done we will truly be living in a country much more like Roosevelt’s in 1933, or Eisenhower’s in 1953, or Lyndon Johnson’s in 1965, or Reagan’s in 1981 (post-assassination attempt). Those were periods of time when real change could happen. A lot depends on our getting that chance.