On the eve of Fox News Channel’s Donald Trump-less Republican primary debate in Iowa, a visit from the GOP front-runner helped boost ratings Wednesday for the network’s “The O’Reilly Factor.”

According to Nielsen estimates, “The O’Reilly Factor” was the most-watched program on cable Wednesday night, drawing 3.793 million, including 642,000 in the 25-54 demo. Compared with its prior January average on Wednesday, the show spiked by 16% in total viewers (3.78 million vs. 3.26 million) and by 23% in the demo (642,000 vs. 524,000).

In both categories, these are the best “Factor” numbers since the night after the San Bernardino terrorist attack on Dec. 2. last year.

“The O’Reilly Factor” is coming off an especially strong frame last week, as it averaged 3.4 million viewers and saw two of its telecasts rank among the week’s top 10 cable programs. Fox News Channel led all cable networks for the week in total viewers, both in primetime (2.1 million) and on a total-day basis (1.3 million).

Trump on Tuesday announced that he would not attend Thursday’s debate over his objections to Fox News Channel’s anchor and debate moderator Megyn Kelly. “Megyn Kelly’s really biased against me,” he said in an Instagram video that day. “She knows that. I know that. Everybody knows that. Do you really think she can be fair at a debate?”

On Wednesday’s show, Bill O’Reilly tried to persuade Trump to reconsider and attend the debate. “You are depriving people of seeing you in a forum they want to see you in,” O’Reilly said to Trump before asking him point blank if he’d reconsider. “You and I had an agreement that you would not ask me that,” responded Trump.

While the GOP candidates (minus the front-runner) will be debating tonight in Des Moines, Trump he will be holding a rally to raise money for veterans groups. Both MSNBC and CNN planned to incorporate the event into their regular programs in the 9 o’clock hour tonight.

Tonight’s main-event debate is slated for 9 p.m. ET and will feature Ted Cruz, Marco Rubio, Ben Carson, Jeb Bush, Chris Christie, John Kasich and Rand Paul. The undercard, featuring Carly Fiorina, Mike Huckabee, Rick Santorum and Jim Gilmore, will air at 7 p.m. ET on Fox News Channel.Joining Megyn Kelly asking the questions tonight will be her FNC colleagues Bret Baier and Chris Wallace. The trio were on hand last August when the first GOP debate of the season drew a record-setting 24 million viewers on the network.