5 things to watch for in the GOP debate, even without Donald Trump

Attendees' shadows are cast on the Iowa flag at a town hall for Florida Sen. Marco Rubio in West Des Moines on Tuesday.

Attendees’ shadows are cast on the Iowa flag at a town hall for Florida Sen. Marco Rubio in West Des Moines on Tuesday.

(Patrick Semansky / Associated Press)

The uproar caused by Donald Trump’s decision to skip Thursday’s GOP debate throws a new level of uncertainty into what was already expected to be a volatile last stand in Iowa before next week’s caucuses.

Trump is expected to loom large, even if he keeps his promise to ditch the event for his own competing one, a fundraiser for veterans. Expect the candidates to talk about him early and often — bashing him for the failure to show up, but debating the very issues he has made dominant: immigration, the fight against Islamic State terrorists, making the country great again.

Here are five things to watch for, even without Trump (and assuming no last-minute change of his mind):

Trump’s super-sized presence, in absentia

Trump says he’s skipping the debate because Fox News has treated him unfairly, mocking him over his complaints about anchor Megyn Kelly, who will be one of the moderators.

But even in his absence, Trump will command his typical oversize presence, which will be both a positive and negative for the front-runner.

Without being there to defend himself, Trump becomes an easy mark. Look for open season on the billionaire, with Trump-bashing over the issues, the no-show — which may not please Iowans’ strong work ethic — and for avoiding questions from a woman.

At the same time, watch for Trump to respond, either from his own event or on Twitter, where he can be expected to unleash one of his trademark tweet storms.

One thing Trump will not likely be: quiet.

Everyone is likely to dog-pile on Trump — and Cruz

Sen. Ted Cruz (R-Texas) briefly overcame Trump for the No. 1 spot in Iowa polls, sparking a bitter fight between the two. New questions about Trump’s marital infidelity and past support of abortion are easy attack lines, especially as Cruz tries to peel away evangelical support.

But Cruz won’t have the stage to himself, even if he gets the center podium.

Expect Cruz, Sen. Marco Rubio of Florida — the next-closest rival — and the others to pile on Trump and to fight it out over national security, immigration, taxes, healthcare and who is the best-prepared and most conservative leader.

Rubio’s shift from optimist to pessimist, and back again

Hoping for a strong third-place finish in Iowa, Rubio has shelved his sunny optimism for a tougher campaign-trail message. Rubio wants Iowans to see him as commander-in-chief potential. But gloom-and-doom hasn’t been his strong suit. Watch for Rubio to return to a more upbeat closing argument to remind voters why he was once touted as the GOP’s best hope.

Bush needs a rationale; Christie needs a boost

This year of the outsider has not been a good one for the governors running for president. Look for former Florida Gov. Jeb Bush, who is not known for throwing punches, to square his shoulders and give voters a reason to get behind his campaign. Gov. Chris Christie of New Jersey has been faring better in polls in New Hampshire than Iowa. But Christie needs to bolster his chances there by not losing badly in the Hawkeye State. Expect the plain-spoken Christie to mix it up to score some points.

Clinton looms large, too

Because this is the final debate before the Iowa caucuses Monday, the candidates will also try to convince voters that they are best suited to defeat Democrat Hillary Clinton. The former secretary of State has always loomed large over the GOP debates. Expect lots of attacks on Democrats, including Clinton and rival Sen. Bernie Sanders of Vermont, as Republicans try to move past the bitter primary season toward the general election.

Twitter: @LisaMascaro