Michael Heseltine, the former Deputy Prime Minister, wasted no time in suggestingthat Mr Portillo could launch a bid for Mr Hague's job after the next general election.
His comments came as bookmakers William Hill put the former Secretary of State for Defence as their 6-4 favourite to be next leader of the Conservative Party.
Mr Portillo attempted to shrug off talk of a leadership bid as he declared his firm loyalty to Mr Hague on a victory walkabout tour of the constituency.
But Mr Heseltine, who in June warned the Tory leader to "watch his back" if Mr Portillo returned to Westminster, sparked fresh controversy with a hint that a challenge would take place after the election.
"I believe that in this Parliament, his loyalty is absolutely bedded in concrete. Nobody knows what happens in the next Parliament," he told the BBC's World at One.
In a jibe at the quality of the current Shadow Cabinet, Mr Heseltine also made plain that Mr Hague should give his potential rival a frontbench job as soon as possible.
"There will be nothing but speculation until that matter is resolved and what's the point of mucking about. Everyone knows his qualities and we are not exactly over-burdened with them," he said.
Mr Portillo held the safe Tory seat with a majority of 6,706, down on Alan Clark's 9,519 majority at the last general election. But with a low turn-out of just 29.8 per cent, Mr Portillo's victory represented a swing of 4.35 per cent from Labour to the Conservatives and gave Mr Hague a much-need boost at the end of a week of stories about the Archer and Ashcroft affairs.
Ian McCartney, a Cabinet Office minister, sought to increase the turmoil in the Tory party by claiming that Mr Hague now had a "stalker" on the backbenches. But Mr Portillo brushed off the speculation, declaring that he was a "loyal supporter" of his party leader.
Mr Hague himself welcomed the return of the former minister, although he appeared to be in no hurry to return Mr Portillo to the frontbench.
"There won't be any immediate changes to the Shadow Cabinet. We've got a new and talented Member of Parliament and I think he will be a great ally for me and a great asset for the party," Mr Hague said.
"He gives me tremendous support. He's got great qualities and great talents and we want to make sure these talents are used in the party," he said.
On his walkabout yesterday, Mr Portillo revealed that he was backing Steve Norris for the Tory candidacy for Mayor of London. "I'm a bit of a Steve Norris fan and I very much hope he continues his candidacy," he said.
Mr Portillo's comments put him at odds with Ann Widdecombe, the shadow Home Secretary, who earlier this week suggested that Mr Norris was unsuitable for the job.Reuse content