Why the cult of Reagan still rules in Washington

In his centenary year, the late President is more influential than ever – even among Democrats.

This weekend, on what would be his 100th birthday, there is no escaping him. His face adorned the entire back page of yesterday's Washington Post (in an ad for General Electric, it should be said). The US Post Office is about to issue a new stamp in his honour, while scholars hold learned symposia to debate his legacy.

Lavishly sentimental ceremonies will be held at his Presidential library in California, while potential Republican candidates for 2012 swoon at the mere mention of his name. Even Barack Obama right now seems to be sitting at the feet of the master.

The master in question, of course, is Ronald Reagan. He might have died seven years ago, in the solitude of Alzheimer's disease, while the political era to which he gave his name appeared to have died with the election of Barack Obama in 2008, amid the wreckage of a financial crisis largely brought on by the unregulated laissez-faire economics he championed. Yet close your eyes and, for a moment at least, Reagan might be alive and well and sitting in the Oval Office. For Republicans he is a patron saint. Sarah Palin and Newt Gingrich, both potential contenders for the White House, will be at Simi Valley for Sunday's festivities. Reagan is the name on the banner carried by conservatives who have largely taken over the party. Even George W Bush ignored his father to swear ideological fealty to him.

But veneration is not confined to Republicans. Even among those who used to excoriate "the Gipper" – for swelling budget deficits; for his indifference to the plight of the less fortunate; for his support of dreadful regimes in Central America and elsewhere and his neglect of the tedious, day-to-day chores of governing – Reagan's stock is rising. When he left office, he was deemed an average president at best. Today, polls of historians frequently put him among the top 10. Not in the very top bracket with Washington, Lincoln and FDR, but solidly in the second tier, in the company of Harry Truman, Dwight Eisenhower, Woodrow Wilson and the like. Obama himself has often evoked the 40th president and he has sought to borrow a little of Reagan's magic to improve his own chances of a second term. During the 2008 campaign he enraged the Clintons by claiming that, whatever you thought of him, Reagan had been a "consequential" president and certainly more so than the husband of his great rival for the Democratic nomination. Indeed Obama, by his own admission, had conceived a grudging admiration for the skills of a politician with whom ideologically he could scarcely have been more at odds. "Reagan recognized the American people's hunger for accountability and change," the president wrote in USA Today.

But none of this quite explains why the man once described as an "amiable dunce" by Democratic presidential adviser Clark Clifford today exerts so powerful a hold on the US. The reasons are several. For one, history has vindicated him. In Isaiah Berlin's distinction between hedgehogs who know one big thing and foxes who know myriad little things, Reagan is indisputably in the first category. He knew one big, basic thing – Communism is bad, freedom is good. At the time, in the early 1980s, he was mocked by liberal intellectuals for branding the USSR an "evil empire" and declaring that Communism would end up "on the ash heap of history." And yet – in some measure thanks to Reagan – it did. It was the same Reagan who negotiated sweeping arms reduction treaties with Moscow and who, at a summit in Reykjavik in 1986, came close to a deal with Mikhail Gorbachev to get rid of nuclear weapons, period. The dunce, it turned out, was also a visionary. Second, Reagan exuded optimism; more attractive than ever now, when that defining American quality is in rather short supply.

He believed fervently in US exceptionalism; that his country was the "shining city on a hill", a unique moral beacon to the world. This was precisely the mantle Obama tried to wrap around himself in his State of the Union address 11 days ago, when he extolled America as "the story of ordinary people who dare to dream", and told his compatriots that "the future is ours to win". Such sentiments ring hollow to jaundiced European ears, but not in the US, even when the chatter is all about "declinism".

Finally, Reagan understood the monarchical aspect of the presidency, so often overlooked, while remaining a man of the people. His Hollywood veneer often obscures the fact he grew up in smalltown Illinois, where he was born on 6 February 1911, a product of common-sensical mid-west America. This background gave Reagan an understanding of Americans and of how to lead them. As Ken Duberstein, his former chief of staff put it recently, his boss grasped that "the job of the President is not to build consensus in Washington but to build consensus in America, and then Washington will follow".

Obama spent much of his first two years trying to do the former, with little success. Now he has met Duberstein to learn the Reagan way and is travelling around the country to take his message directly to the citizenry, rather than via politicians on Capitol Hill. The comparisons should not be overstated. Reagan's triumphant 1984 re-election was sealed by a surging recovery of the economy; Obama will do well to be as lucky. After his mid-term reverses, Obama may be moving to the centre, cutting taxes and bringing business types into the White House, but thereafter the approaches and philosophies of the two diverge. Reagan memorably described government as "not the solution but the problem". For the 44th president, efficient and involved government is vital if the country is to get back on its feet. For all his rhetorical skills, the analytical, cerebral Obama does not convince as an optimist. That's why Americans most miss Ronald Reagan.