1. Obama matches up poorly with John McCain in terms of national security issues. Yes, he was "right" on Iraq, if you go by a speech he gave as a state senator in Illinois--one that was rather hard to find in the early days of the war, when it seemed we were "winning." (Sen. Obama has possibly gotten more mileage out of one anti-war speech than any state senator in history.) This is an advantage in Democratic caucuses, which has a strong anti-war constituency, but a liability against someone like McCain who will be hailing the "surge" and calling for "success" in Iraq.
Yes, I know that the surge is not responsible for the decline of violence in Iraq. The violence has declined because we paid the Sunnis to fight al-Qaeda instead of Shi'ites, and because Moqtada al-Sadr called for the Mahdi Army to stand down (temporarily).
And yes, I also know that 60% of the American people think the war was a bad idea. Those numbers start to dwindle, however, when you start getting more specific about what to do about it. Only about 20% want to pull out immediately. Trying to talk your way back from an extreme anti-war position is going to be hard to do against a war hero who promises victory.
Hillary, on the other hand, is already seen by voters as being ready to be commander-in-chief. Couple that public perception with her eight years on the Senate Armed Services Committee, and you have a candidate who can go toe-to-toe with John McCain. Yes, she has a vote or two on her Senate record that I wish had gone the other way--so does Obama. On the other hand, it is precisely those votes which make her attractive to moderates and some Republicans.
2. Hillary is much stronger on the economy, and the economy is going to be more and more of an issue as the year progresses. Unemployment is rising. House prices are falling. We may already be in a recession, and it could get deep.
Meanwhile, John McCain has already said he doesn't know much about economics, and said he'd "read Greenspan's book" to bone up. (If you were only going to read one book to "bone up," that wouldn't be the one.)
It's going to be the economy, my friends, and Hillary's fight, and get-things-done wonkiness, is going to start looking better and better. Plus, the Clinton brand name is already associated with broad-based prosperity and sound economic management. Big advantage Hillary.
3. In both primaries and caucuses, Obama does quite well among well-educated affluent whites, but loses soundly to Hillary among minorities and the poor--the Starbucks crowd vs. the Dunkin' Donuts crowd, as Gerard Baker of the Times of London put it.
Clinton is the candidate of "those who do not have money to waste on multiple-hyphenated coffee drinks--double-top, no-foam, non-fat lattes and the like. Not for them the bran muffins or the biscotti. They are the 75-cent coffee and doughnut crowd."
In a race against Obama, McCain could make a strong appeal for the Latino vote. Latinos see McCain as a friend on immigration. If McCain even got 40% of the Latino vote, we wouldn't have a chance in the southwest or Florida. This would be disastrous for the Democratic Party, not only this year, but in the future as well. The Democratic Party cannot win without the votes of minorities and poor people, and shouldn't.
4. That Kennedy/Hollywood business won't work in the general. (It didn't even work in California--or Massachusetts.) By the time the GOP gets done hanging Ted Kennedy around Obama's neck, Kennedy might as well be Obama's running mate. Nothing against Ted, but there go the red states that Obama's supposed to pull in. (RFK Jr. helps, but--oops--he's for Hillary.)
5. Sen. Obama runs well in open primaries and caucuses where independents can vote. He regularly loses in closed primaries where only Democrats can vote, and polls some twenty points below Hillary among self-identified Democratic voters. What difference does this make in a general election? Traditional Democrats would likely vote for Obama, but with less enthusiasm which could affect turnout, which is a critical factor in big must-win states. That business about how Ronald Reagan was a "transformative" president, and how the GOP was the "party of ideas" during the Clinton administration, leaves them cold. Yes, Sen. Obama is "likeable" among Democrats--I like him anyway--but is he "likeable enough"?