WASHINGTON (REUTERS) - The Fox News debate without front-runner Donald Trump attracted the second-smallest audience of the seven such televised encounters among Republicans so far this election cycle, according to early ratings figures released on Friday.
According to preliminary Nielsen data, 12.5 million people watched the Republican face-off, beating only an earlier debate on the less-prominent Fox Business Network.
But Thursday's encounter was one of Fox News' biggest-ever hits and drew more viewers than coverage of a rally at the same time that was hosted by Trump.
The billionaire refused to participate in the debate out of anger that Fox News anchor Megyn Kelly was a moderator.
Last-minute phone calls with Fox News chairman Roger Ailes failed to resolve their dispute, which broke out just days before next week's Iowa caucuses, the first nominating contest for the Nov 8 presidential election.
Instead, Trump held his own rally in Iowa at the same time as the debate, which he promoted as a way to raise money for charity.
CNN gave partial coverage to his event.
On Friday, Trump defended his decision to snub Fox News, the most powerful media force in Republican politics.
"I have a very good relationship with Fox, but when somebody doesn't treat you properly, you've got to be tough," he said at a rally in New Hampshire.
Trump often claims on the campaign trail that he is responsible for strong viewership of Republican debates. And he managed to upstage the debate to a certain extent, dominating Twitter mentions and Google searches during the event.
Despite Trump's absence, Thursday's debate was the second-largest audience ever for a Fox News programme, beaten only by the first Republican presidential debate in 2015 with 24 million viewers.
It was also the most-watched programme on TV on Thursday night, Fox News said.
"The debate topped all TV Thursday night in total viewers including all broadcast shows," Fox News said in a statement.
Audiences for all Republican debates in the current presidential election campaign have been much higher than in previous years.
Viewership has since tapered, with 18 million people watching a CNN-hosted Republican debate in December. The Fox Business event earlier this month drew the smallest crowd with 11 million viewers.