The Welsh Ukip leader argued the party was not “dying” but instead was “doing better than Labour” despite now having no representatives inside the Commons.
His comments were promoted as Douglas Carswell quit Ukip on Saturday to continue his term as an independent MP.
The Clacton politician said he no longer needed to be part of the anti-EU party as Brexit is “certain” ahead of Theresa May triggering Article 50 on Wednesday.
However, Mr Hamilton rebuked the claim, as he warned there was more the Ukip than “just Brexit”.
Neil Hamilton remained defiant after Douglas Carswell quit the party on Saturday
We got four million votes in the general election in 2015
Speaking to talkRADIO on Monday, he said: “We’re on about 12 per cent at the polls at the minute, which compares very respectively with the Labour party.
“We got four million votes in the general election in 2015 and there’s every reason to believe that once we start concentrating once again on domestic politics, as opposed to the European issues, and when Theresa May fails to deliver on immigration issues, that Ukip will recover its position and indeed enhance it.”
Mr Carswell, who defected from the Conservatives in 2014, is adamant he does not need to call a by-election because he isn’t “switching parties”.
There has, however, been calls from senior Ukip figures, including Nigel Farage, for a fresh ballot to be held in the Essex seaside resort.
Neil Hamilton argued Ukip was more than just Brexit
The Clacton MP split opinion since joining the party three years ago due to his more liberal views on topics such as immigration.
The tensions recently came to a head with Mr Carswell, Mr Farage and party donor Arron Banks, after a spat over allegations that Mr Carswell tried to block a knighthood for the party’s former leader.
Continuing in his interview, Mr Hamilton said he found it odd Mr Carswell had chosen now to resign from Ukip.
The many faces of Nigel Farage Mon, March 27, 2017
UKIP leader Nigel Farage is certainly animated!
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Nigel Farage arrives at BBC Broadcasting House in London
He said: “I regret Douglas’ departure and I’m rather mystified by it because he doesn’t seem to have any quarrel with Paul Nuttall, the current leader of Ukip.
“He doesn’t seem to disagree with Ukip on matters of policy. He did, however, disagree with Nigel Farage about the tone and temperament of the way in which Nigel expressed his arguments.
“But as far as I can see, Douglas doesn’t really have any quarrel about any policy with us in any shape or form, so I can’t really understand why he has now resigned.”