DES MOINES, Iowa- For the Republican candidates for president, it was a glimpse of what could have been.

Front-runner 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 their approach to governing.

And for some candidates, Trump's absence from the debate stage Thursday night appeared to ease some of the tension created by his sharply personal attacks.

Iowa voters kick off the 2016 nominating process Monday, offering the first indications of whether Trump's abrupt decision to skip the debate will have any impact on his standing atop the GOP field.

His lead in Iowa had already been more tenuous, with Texas Sen. Ted Cruz pulling support from conservative and evangelical voters.