It’s hard to contest the view that Mitt Romney is losing. He’s trailing in all national polls, including ones friendly to Republicans, like Rasmussen. He’s trailing in all swing state polls, and the latest Post polls show him on the verge of losing in critical states like Ohio and perhaps even Florida. He’s at a cash disadvantage against President Obama, and conservative Super PACs lack the focus and direction necessary to make a real impact. And of course, Obama maintains an on-the-ground advantage. In the ten states most likely to determine the election, Obama has a 2-to-1 lead in field offices.

Still, lots of campaigns go through hard times. The question is whether Romney can win. Writing in the Wall Street Journal, Gerald Seib makes a case that echoes the pundit consensus: yes, Romney is behind, but six weeks — the time between now and November 6 — is an “eternity” in politics.

Seib offers three reasons for why we should see this as a close race. First, that Republican voters are highly motivated for the election. He cites the latest Wall Street Journal/NBC News poll, which finds:

But among those who voice the highest interest in the election — in other words, those who seem most intensely interested in voting — Mr. Romney leads by three percentage points.

It’s true that the most interested voters — who also tend to be the most enthusiastic voters — lean Republican. But the poll shows a likely voter electorate that’s very similar — if not identical — to the registered voter pool. Among registered voters, Obama leads by 6 points, 50-44. Among likely voters, that lead narrows — slightly — to 50–45. If the Democratic National Convention did anything, it closed the enthusiasm gap, which is part of why Obama leads in all polls of likely voters.

Seib cites two other factors: Romney’s strong support among conservative voters, and undecided voters, who are less-than-warm toward President Obama, and willing to give Romney a chance. But strong conservative support is a given — it’s rare that partisans don’t vote en mass for their nominee. And while it’s possible the poor economy may lead undecided voters — who tend to be less informed the general population — to break toward Romney in the final weeks of the campaign, I have my doubts. As Nate Silver points out, the general trend is for undecided voters to break toward the incumbent in the last stretch of the election; barring intolerable conditions, low-information voters almost always vote for the candidate they know.

I don’t want to overstate the extent to which we can predict the final outcome of this election. Anything can happen. In The Timeline of Presidential Elections, political scientists Robert Erikson and Christopher Wlezien note that the final week can see a significant amount of change. Still, there’s no escaping the fact that Romney faces long odds. He doesn’t hold a lead in any of the states he needs to win, and he’s lost his advantage on the economy. Yes, the debates remain, but what we know says that they will have a marginal effect on the outcome. And with few exceptions, the leader in late September has always gone on to win in November.

Pundits continue to say that this is a close race that Romney could still win. That’s true in the broadest sense — by virtue of winning the nomination, Romney always had a decent shot of winning the presidency. But he’s now a long shot.

Jamelle Bouie is a staff writer at The American Prospect. You can find his blog here.