For the GOP candidates seeking the Republican nomination for a presidential run, it was a glimpse of what could have been at last nights debate.

Donald Trump speaks to veterans at Drake University on January 28, 2016 in Des Moines, Iowa. (Photo by Christopher Furlong/Getty Images)

Donald Trump's boycott of the final debate before the Iowa caucuses created space for his rivals to delve more deeply into their differences on immigration, foreign policy, and governing.

For some candidates, especially former Florida Gov. Jeb Bush, Trump's absence appeared to ease some of the tension created by his sharp attacks.

Much of the focus was on Ted Cruz and Marco Rubio, who under-performed in the debate.

Bush and New Jersey Gov. Chris Christie, along with Ohio Gov. John Kasich, are looking beyond Iowa and hoping New Hampshire's primary jump-starts their campaigns.