[T]here's a top two—Hillary Clinton and Barack Obama for the Democrats, Rudy Giuliani and John McCain for the Republicans. There's a third-place candidate on the edge of the first tier—John Edwards and Mitt Romney. There's a big jump down to the next tier of declared candidates, none of whom seem to have much of a chance. And there is a possible late entry (Al Gore) or two (Fred Thompson and Newt Gingrich), any of whom would join the first tier.And a way in which they are different:
The Democratic campaign has been amazingly stable. In late February, if one averaged half a dozen national polls, Clinton was at about 35%, Obama had about 25%, and Edwards and Gore trailed with about 13%...Kristol wants to think the more volatile condition is better. But is it?
The Republican race has been more volatile....
[W]hereas three-fifths of the Democratic vote now goes to the two front-runners, fewer than half of Republicans support Giuliani or McCain.... The door is open far wider for Thompson—and perhaps Gingrich—to enter the G.O.P. race than it is for Gore to join the Democratic contest.
And the G.O.P. race features real differences among the candidates on important and salient issues [like abortion and immigration].