Tonight’s debate is the second-to-last one before Iowa, and the dynamics are a little different:

Donald Trump and Ted Cruz are finally going after each other on the campaign trail, because they are running neck and neck in Iowa.  In Iowa, if the polls can be believed (and I’m not sure polls are as reliable this year), Trump has perhaps a slight edge, but Cruz is within the margins of error.  Trump still enjoys a 15 or so point lead in New Hampshire, although if Cruz does well tonight, the last debate, and in Iowa. that could change.  Expect the Fox Business Network moderators—who are on their second debate of the season — to draw the two of them into a fight onstage at the debate.  I don’t think Cruz will take the bait in a debate forum.  The issue of Cruz’s birthplace (a silly non-issue) as well as some filing/loan irregularities will be brought up.

With Trump and Cruz fighting for the outsider mantle, Jeb Bush, Marco Rubio, John Kasich, and Chris Christie are all trying to climb over one another to emerge as the establishment candidate.

The campaigns of both Rubio and Christie, but mostly Rubio, are a bit like an old car trying to start up.  The engine runs a little bit and dies.

Bush and Kasich, on the other hand, seem to have flooded their engine.  They just can’t get up there.

And then there’s Carson, once the poll leader ahead of Trump.  He’s plummeted and down there with Rubio and company.

Rand Paul and Carly Fiorina have been kicked down to the kiddie table debate, with Paul saying he won’t show up.