I've been hearing regularly, both from TV pundits and in general conversation, that it would be premature to declare Sen. Hillary Clinton the nominee, because Howard Dean was way out in front this time in 2003, and "anything can happen" between now and when votes are actually cast.

All technically true, but there are big differences between the Clinton '08 and Dean '04 campaigns.

Dean was a relatively unknown, outsider candidate who hadn't been tested on the national stage. He was more vulnerable to attacks and more prone to make mistakes.

Clinton is quite well-known, well-tested and thoroughly vetted.

It is highly unlikely there will a surprise scandal. Because people are familiar with her, little things (Norman Hsu, Hillary's laugh) are harder to blow up into big things. She doesn't make many mistakes, and when she does, she recovers quickly.

She is addressing the main concern most Dem voters had with her: the fear that she can't win. She polls well against GOP possibilities, often better than other Dems. Any argument that she can't win is merely theoretical.

I don't chronicle the above evidence in Clinton's favor to cheerlead, especially since my recent Clinton posts have been quite critical of her.

I do so to emphasize that anyone who is less than enthusiastic about her potential nomination should not dupe themselves into thinking that just because "anything can happen" means it is likely something will.

Someone is going to have to make something happen.

Last month I posed the question "Has Hillary Peaked?" because of the attention being paid to her opening the door to leaving troops in Iraq by 2013 and beyond. The short-term answer is clearly "No," in large part because Obama and Edwards adopted the same position, failing to take advantage of the biggest opening she gave them.

(Edwards is trying to carve out a different point of contrast, stressing he would only leave a few thousand troops for limited non-combat missions, but it's a nuanced point that has been muddled by the refusal to take the 2013 pledge.)

Gov. Bill Richardson and Sen. Chris Dodd are now trying to jump into the first-tier by attacking all three of them for failing to take the 2013 pledge.

But it is harder to take on three people at once than isolate a single candidate.

There are not a lot of issues that present a major contrast and are significant enough to make a voter question why Clinton shouldn't be the frontrunner.

If it's not going to be Iraq, it's hard to see what other openings exist.

Finding them is the challenge for Clinton's rivals, and anyone else who believes she would not be a best champion for liberal principles and policies at home and abroad.