Fox News said the advertiser departures had not caused the network to suffer a financial hit over all, noting that the commercials that would have run nationwide on “Tucker Carlson Tonight” had moved to other programs on the network.
On Thursday night, a hashtag campaign — #IStandWithTucker — sprang up on Twitter, with his fans appending it to messages of support for the host. As the phrase made the list of the platform’s trending topics, Mr. Carlson’s detractors tweeted insults at the host and the network that employs him while making use of the same hashtag.
Mr. Carlson, who recently sold his stake in the conservative site The Daily Caller, has lost major advertisers in the past few years. Dozens of companies, including Pacific Life, Farmers Insurance and IHOP, have distanced themselves after his on-air comments about white supremacy, immigrants and women.
But his show remains a linchpin of the Fox News lineup, drawing 4.8 million viewers last week. So far this year, “Tucker Carlson Tonight” generated 16 percent of ad revenue for Fox News, according to iSpot.tv, the television ads measurement company. Out of $75 million in total spending, more than a third came from a single advertiser: MyPillow, a pillow manufacturer in Minnesota run by Mike Lindell, a supporter of Mr. Trump who appeared at a White House Rose Garden news briefing in March.
This month, Mr. Carlson has so far attracted 20 percent of Fox News’s ad revenue, compared with 11 percent during the same period last year. (Fox News said that figure was not accurate, but declined to provide corroborating data.)
Few major brands remain on Mr. Carlson’s program. Several major media buyers said they did not have clients with recent spots on the show.
Alongside spots from the computer security brand Norton, the skin care brand Proactiv and Mr. Trump’s re-election campaign, recent ads have included a beet powder company that has used the gun rights personality Dana Loesch as a spokeswoman, a foot fungus treatment brand and several law firms, according to iSpot.tv.