Mr Hague, 44, has been on the backbenches since standing down as leader after the party's heavy defeat at the 2001 election.
But he has told friends that he is ready to play his part in the drive to beat Labour. He does not want to be seen as an "absentee grandee" like Kenneth Clarke, who has angered some Tory MPs by declining to serve on the frontbench since the party lost office in 1997.
One ally of Mr Hague said: "His appetite for politics is undiminished and he is thinking hard about coming back to do his bit. He's the best Commons performer of his generation and we can't afford to leave him on the sidelines."
Whoever wins the Tory leadership is expected to offer Mr Hague a senior post such as shadow Foreign Secretary, shadow Chancellor or shadow Home Secretary. He would not have to give up all of his business activities but would have to ensure there was no conflict of interest.
Yesterday Mr Hague rallied the Tory conference and won a standing ovation after launching a powerful attack on Labour. Although there has been speculation that he might one day make a remarkable comeback as Tory leader, he said his only ambition was to see the party return to power.
"When you have [been leader] for four years, mere personal ambition becomes not only unsatisfying but irrelevant and all that remains, faced with a government whose words are so twisted and distortions so profound that they have debased the very coinage of politics, is the ambition that our country will once again be served by a Conservative Government - and that is my only ambition today."
He did not favour any candidate in the leadership race, and said: "Let the judgment of history on our own party in 2005 be this - that we raised our gaze from our navels and braced ourselves to prepare our country for the great economic, social and environmental challenges of a new century."
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