Gregor Mackay, 30, was replaced as Mr Hague's chief spin doctor by Amanda Platell, 42, a former editor of the Sunday Express, and ex-managing editor of The Independent and Independent on Sunday. She is not a member of the Conservative Party.
Mr Mackay's dismissal is a sign of jitters in the Tory hierarchy. Even Mr Hague's allies admit he may face a crisis of confidence in his leadership if the party does badly in local elections in May and the European parliament poll in June.
Ms Platell dismissed rumours that she supported the single currency at a recent public meeting.
She admitted being briefed by Labour officials before going on BBC's Question Time in 1994, saying this was standard practice at the Labour- supporting Daily Mirror, where she then worked.
Mr Mackay was not available for comment but told friends he was fired, after turning up for work yesterday, without any inkling that Mr Hague wanted to dispense with his services.
Mr Mackay appears to have paid the price for Mr Hague's failure to dent Labour's opinion-poll lead and boost his poor personal ratings.
Some shadow cabinet ministers are understood to have urged Mr Hague to sack Mr Mackay after press reports that the Tory leader might dismiss "old-guard" figures from his frontbench team who reminded voters of John Major's government. Mr Mackay was also blamed for a shambolic Conservative Party conference in October.
Ms Platell, who starts work today as the party's head of news and media, said: "I have a very good understanding of Middle England and what the voters there care about. As a woman, I will be able to bring in a fresh perspective."
She lost her job at the Sunday Express, which has swung behind Labour since the general election, during fall-out over an interview with a Brazilian friend of Peter Mandelson, the former cabinet minister
The Tories insisted that Mr Mackay was "leaving at his own request to pursue other interests" and Mr Hague paid tribute to his "invaluable contribution."
Mr Mackay turned down the offer of another post with the Tories.
"It's very hard on Gregor - a classic case of shooting the messenger," said one Conservative Central Office insider. "Perhaps the problem is with the product rather than the marketing man."Reuse content