It was the coup that never was. A black Conservative MP who was named on Sunday as a surprise candidate to succeed David Cameron in two right-leaning newspapers has been forced to deny that he could be a "stalking horse candidate" who might bring down the prime minister.

Adam Afriyie, the suave multimillionaire MP for Windsor, has been reportedly groomed as a replacement for the prime minister if the Tories fail to deliver a majority government in 2015.

Tellingly, both the Mail on Sunday and the Sunday Times claimed that he had a campaign team in place and that backbenchers are being asked to sign a pledge of their support in expectation of a future leadership challenge.

But after several hours of speculation, Afriyie appeared on Sky News to say that he had held regular talks with colleagues "about the long-term future of the party" but rejected suggestions that he was being lined up as part of any plot to oust its leader.

"I will never stand against David Cameron, I am 100% supportive of David Cameron and I am working with many colleagues but to make sure we give the Conservatives the best chance of winning the May elections, the euro elections and the 2015 election," he told Sky News.

"When you are working with an organised team to try to achieve something positive for the party and for David Cameron it is inevitable that all sorts of rumours leak out.

"There is not truth to any of it. We are working very hard to keep David Cameron secure, to make sure there is not a vacancy and to make sure he has the best chance of all of winning the upcoming election," he said.

The newspaper reports and Afriyie's decision to issue a qualified denial of them, will concern Downing Street. The prime minister's supporters have been trying to argue this week that he has won over the parliamentary party with a promise for a future an in/out referendum over membership of the European Union.

Afriyie, who is worth between £50m and £100m, grew up in poverty in Peckham, south-east London, the son of an English mother and a Ghanaian father. It has been claimed that he went to a tough state school and sometimes went hungry as a child. Elected in 2005, he was the first black Tory MP and had a brief stint in the shadow cabinet but was overlooked for the cabinet when the coalition came into power.

He has never claimed parliamentary expenses for travel or a second home.

Blaming a "quiet news weekend" for the rash of stories about moves to line him up as the next leader, Afriyie said colleagues "right now" were united behind Cameron. "I work with many dozens of colleagues both on Conservative party policy for 2015 – in Conservatives 2020 group – and many other groups within the party.

"Of course we talk about the long-term future of the party and the long-term success of the party because we think it is the best thing for the British people.

"But right now, right now, we are 100% behind David Cameron."

Senior Conservatives said privately that he is being spoken of as a potential replacement for Cameron and said that he has an "informal" team of backers in place.

One MP: "There is some headwind behind Adam … It's an advantage that he is not posh. He is so far from the 'Toffs' who currently dominate [the party]."

Another said: "I was pulled into the smoking room a few weeks ago and took part in a murmured chat about who we would support against Cameron in the future. The three MPs with me said they would be supporting Adam. It was like something out of Secret Army," he said.

MP Mark Field told the Mail on Sunday that he had "a handful of conversations with people" but that there was "no mass campaign" in support of Afriyie.

"Discussing him as a long-term option has nothing to do with destabilising the coalition or plotting against the current leadership," he said.

Afriyie's supporters are now concerned that this weekend's reports may scupper any future leadership bid. One said: "This has made a future challenge that little bit harder," he said.