Steve Chapman’s column yesterday examines why the general election might be tough on John McCain. The president’s disapproval numbers are at a historical low, since the Gallup poll began decades ago. Combine this with an unpopular war and a rough economy and you have all the necessary conditions for a “repudiation” of the Republican Party.

And yet, I find this agrument (which has been made by others) to be perilously conventional. I don’t want to carry water for McCain and I certainly would not argue the campaign will be “easy,” but if Democrats think their ascendancy is a foregone conclusion, they’re committing a fatal conceit.

For one, it’s not clear to me that McCain will be held accountable for the Republican failures. More and more people are identifying as “independent.” This should make comparisons with previous election difficult because voter behavior is likely to be more unpredictable. Moreover, despite Obama’s dedication to change, McCain may still fair better with independents because he’s actually gone against his party on some issues. Obama has not. One of the reason’s Republicans are so despised right now is their inability to control federal spending. But McCain has been the leading critic on this score.

Second, overall trust in government is down. It often goes unreported that Congressional approval ratings are lower than the President’s. And a poll last year found that overall trust in government is reaching historical lows, rivaling the Watergate era. Yes, Republicans are a big reason for this, but it isn’t exclusively their problem. While GOP Party ID is falling off some, Democrat ID isn’t skyrocketing.

So we have a situation in which the incumbent party is enormously unpopular. And yet, the challenging party isn’t all that popular either. And the incumbent party’s candidate has spent years distancing himself with unpopular elements of his party, while the challenger has the most liberal voting record in the Senate.

If what Americans want is independence, pragmatism, and less partisanship, it may be McCain (despite being Republican) fits the bill better than Obama.