Conservative MP Adam Afriyie has insisted he is "100% supportive" of David Cameron, after several newspapers reported he was being groomed as the next Tory leader.
Mr Afriyie told Sky News he nearly "choked on my cereal" when he read the speculation on Sunday morning.
He said there was "no truth to any of it", adding that he would "never stand" against the PM.
Mr Afriyie said he was "working very hard to keep David Cameron secure".
Several Sunday newspapers reported that Conservative MPs had been approached to endorse Mr Afriyie as a leadership candidate in the event of a contest.
The reports suggested Mr Afriyie was being positioned as a "surprise" candidate in the event the Conservatives lose the 2015 election and Mr Cameron resigns as leader.
Under current Conservative Party rules, a ballot is triggered if 15% of MPs request one.
There are currently 304 Conservative MPs in Parliament, meaning 46 signatures would be needed to trigger a vote.
A self-made millionaire who grew up in Peckham, south London, Mr Afriyie was elected in 2005 for the safe Tory seat of Windsor.
He rejected the suggestion that he was attempting to gather support to oust Mr Cameron, saying "right now" colleagues were united behind the prime minister.
"I will never stand against David Cameron," he said. "I am 100% supportive of David Cameron."
"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."
Asked on Sky News where the rumours might have come from, he said: "It's inevitable that all sorts of rumours leak out, but there's no truth to any of it.
"We are working very hard to keep David Cameron secure, to ensure there is not a vacancy and to make sure he has the best chance possible of winning the upcoming elections.
"Sometimes there can be quiet news weekends and maybe this was just one of them."
Tory 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 Mr Afriyie.
"Discussing him as a long-term option has nothing to do with destabilising the coalition or plotting against the current leadership," he said. "It would be impossible to do that given how the rules operate and counter-productive."
Conservative party chair Grant Shapps confirmed that he had contacted Mr Afriyie about the stories and been told they were "completely untrue".
Former MEP Chris Heaton-Harris, who was elected in 2010, has also denied being involved in a plot.
In a message posted on his website, he said: "I want and expect David Cameron, who I admire hugely and support as party leader completely, to lead the Conservative Party into the next general election and I also fully expect us to win that election.
"I have not, am not and will not support any attempt to remove him as leader of the Conservative Party as I completely believe that he is the right man to lead our country through the difficult times we find ourselves in."
Adam Afriyie, who is mixed race, has been described by some newspapers as a "British Obama".
Mr Afriyie played down the comparison: "We're mixed heritage, we share the same birthday bizarrely, but our politics are very different."