Sammy Wilson has rejected claims from fellow DUP member David McIlveen that support for Arlene Foster is diminishing within the party.
Mr Wilson said there was a lot of admiration for the DUP leader given how she had handled the pressure "along with all the domestic things she has to do".
Former North Antrim MLA McIlveen broke party ranks over the Renewable Heating Incentive scandal.
He said the DUP leader was personally responsible for the fiasco describing it as an “omnishambles”.
In a piece for the News Letter the son of the Rev David McIlveen, the Free Presbyterian minister and close friend of DUP founder Ian Paisley accused the first minister of seriously misjudging public anger on the matter.
He said party members considered Mrs Foster "deeply damaged" and that more were considering her an "electoral liability" and an election centred around her would be impossible.
"Whilst the view in public is that ‘Arlene’s team’ are as loyal and happy as ever, the reality in private is something very different,” he said.
However, in response, DUP MP Sammy Wilson said Mr McIlveen was "sore" over losing his Assembly seat and that he have no evidence of party disquiet for its leader.
"He is totally wrong and has a motive for saying it," the politician told the BBC.
"I find this difficult to understand, he owes a lot to the party he had a public position in being an MLA and when the chips are down feels he has to go with the mob rather than stand by those that have been his friends."
Mr Wilson said it would be up to party members to determine if Mr McIlveen should be disciplined.
"He has expressed a personal point of view and he has added to the media frenzy in all of this - that should not go unnoticed."
Mr Wilson said the First Minister enjoyed the full support of her party and many admired her for how she had handled the matter.
"This would carry weight if it did have evidence to back it up," he said.
"All party members have been supportive of her. Anyone can say that but it is another thing to produce the evidence.
"I have been around the party much longer than David, I've been in it for over 40 years, I've been in daily contact with the people of the party and I have not heard that. Most have been very supportive.
"What I have heard is a lot of sympathy for someone they feel has been treated unfairly, accused unfairly of not having done things or having done things and are rallying behind her especially as the media campaign has been ramped up to try and unseat her and her enemies at Stormont have tried to do this."
Mr Wilson said the DUP leader had his full confidence.
"She has come through a very difficult time," he added.
"All of us that have been involved in politics know the kind of pressure and media exposure she has had over the last number of weeks and months and the effect that can have on an individual.
"And she had handled that magnificently. She has got to balance this along with all the domestic things she has got to do.
"It's an indication of how good a leader and how strong she is.
Mr Wilson said the negative headlines of late was "bound" to have an impact on Mrs Foster's family life, but that it happens to everyone.
"All I am saying is there is a lot of admiration in the party for the way she has handled this."
The MP said Mrs Foster should not "dance to the tune" of Sinn Fein by its calls for her to step aside because she would be "dancing to their tune for the next four years".
And that he was "sure" the DUP leader would be at the helm for the next election.
I have little in common politically with Arlene Foster. From abortion, to marriage equality, it's hard at times to find anything we would agree on, though I met her briefly after the Assembly debate on my case in 2014, and I appreciated the kindness she showed me on that occasion.
Northern Ireland's Renewable Heat Incentive (RHI) scheme is a debacle. "Debacle" is not my word, it is the one Arlene Foster chose when making her infamous statement to the Northern Ireland Assembly before Christmas. If debacle is the right word, then it's because one definition is "a complete failure, particularly because of poor planning and organisation".