President Obama may win re-election, but if he does it appears it will be without the legions of fervent supporters and big enthusiasm that propelled him to victory four years ago.

In the latest Washington Post-ABC News poll, Mitt Romney's supporters are about as enthusiastic about supporting him in November as are those who back Obama. This is a stark contrast from the Post-ABC poll earlier this month, as well as throughout 2008, when Obama had huge leads over Sen. John McCain in this area.

In the new poll, 51 percent of  voters who support Obama are "very enthusiastic" about supporting him, as are 48 percent of Romney backers who are very enthused. Romney came close to Obama on enthusiasm once before, closing the gap to six percentage points in August. 

Compared with four years ago, Obama's supporters are less enthusiastic, while Romney's are clearly more so than were McCain's. Obama's level of intense enthusiasm is down 10 percentage points from late September 2008, when 61 percent were "very enthusiastic." Strong enthusiasm for Romney is 10 points higher than it was for McCain at the same point in the campaign. 

The four-year drop-off in Obama enthusiasm has been most stark among ideological moderates. More than six in 10 moderate Obama voters were "very enthusiastic" about supporting him In a Post-ABC poll at this point in the 2008 campaign. Today, just 42 percent of Obama's moderate voters are highly enthusiastic. Liberals, by contrast, are just as enthusiastic about Obama now (65 percent very enthusiastic) as four years ago (61 percent).

For Romney, the improvements over McCain are among conservatives, older voters and among evangelicals. For instance, a 56 percent majority of white evangelical Protestants are "very enthusiastic" about voting for Romney, up from 36 percent who were jazzed about McCain. The spike among this group may come as a surprise, given that evangelical Christians were among Romney's weaker groups in the Republican primaries this year.

More broadly, while Obama's supporters remain just as enthused as Romney's, enthusiasm is a greater factor in turnout for Obama supporters, a finding in the new poll that mirrors results from an early September Post-ABC survey following the conventions.

Fully 95 percent Obama's "very enthusiastic" supporters say they're absolutely certain to vote, compared with 68 percent of those who are "somewhat" or less enthusiastic. Among Romney supporters, 98 percent of those who are "very enthusiastic" say they are certain to vote, compared with 81 percent of those who are less enthused about Romney.