Nigel Farage last night described Ukip's only MP as "irrelevant" and insisted that he doesn't care if he leaves the party.
Asked whether Carswell, who has publicly fallen out with the Ukip leader, should leave the party he replied: "He can do what he likes. I don't care. He's irrelevant."
Speaking at the Ladbrokes EU referendum debate in central London, Farage insisted that there was no "internal civil war" within the party, adding that every other member was united around the same cause.
"We've got two dozen MEPs united. Hundreds of councillors united. Our three peers united. It would be better if Douglas Carswell saw the world the way we do. He doesn't. It doesn't matter."
Farage and Carswell are believed to no longer be on speaking terms, after the Clacton MP called for Farage to stand down.
Carswell said at the end of last year that the party needed a "fresh face" at the top. Farage responded by calling on Ukip's only MP to "put up or shut up."
Farage's latest comments come after it was reported last month that Carswell faced expulsion from the party after backing a rival campaign to leave the EU.
The majority of Ukip politicians, including Farage support the cross-party group "Grassroots Out" (GO) while Carswell, who defected from the Conservatives in 2014, backs the Vote Leave group.
Farage last night described Vote Leave, which is backed by several Conservative ministers, as the choice of the Westminster establishment, but insisted the split between the two groups would not affect the final result.
Farage also defended his decision to stand alongside George Galloway at a recent GO rally, saying he would "do it again."
He said that Galloway, who he has previously described as "a towering figure of the left," helped attract British Muslims to vote for Brexit. He also called widespread reports of a mass walkout in protest when Galloway stood up to speak at the GO rally a "disgrace".
"I saw your report from that night John," he told John Craig from Sky News in the audience.
"It was an absolute disgrace… People were leaving to get trains… Maybe 150 left. Maybe to get trains."
Those leaving the event told BBC reporters that they were in fact walking out in protest at Galloway's appearance.