If you're a liberal Democrat, that is. George Will makes it:
Large undertakings in domestic policy -- e.g., the enactments of Social Security in 1935 and of Medicare in 1965 -- often follow landslide elections. In the 15 presidential elections since the Second World War, only twice has the Democratic candidate won 50 percent of the popular vote -- Lyndon Johnson emphatically in 1964 and Jimmy Carter narrowly in 1976. In 2008, Obama is more likely than Clinton to win an impressive electoral vote total that will look like a mandate. Conservatives should think: Although Republicans have much to fear in 2008, they might have less to fear from her as a candidate and, if she wins, as a president, than they would from Obama.
Without mentioning Obama by name, I made a similar argument in the Atlantic a couple months ago. After pointing out all the trends going the Democrats' way, I added:
... even slow-motion realignments require architects, and the memory of Ronald Reagan’s role in the Republican revolution, in particular, is a reminder that having a message isn’t enough; you need a messenger as well.
Twice in the past 25 years—in 1986 for the Democrats, in 1994 for the Republicans—an opposition party retook one or both houses of Congress, as the Democrats just did. Each party thought it had a governing majority within reach, but each lost the subsequent presidential election, riding a weak horse to defeat. Long-term trends make new majorities possible, and traumatic events (such as 9/11 and the Iraq War) can help catalyze their formation, but without effective leadership, the opportunities are easily squandered, whether on the campaign trail or in the White House. Just ask Karl Rove and George W. Bush.
I still think this is right, though I'm have to say I'm a little less confident - or worried, more aptly - about Obama's ability to play the Reagan role after watching him campaign for six months.