Labour MPs and peers last night rallied behind Michael Martin, denouncing what they see as a "nasty", "sickening" and "pernicious" campaign to get him ousted as the £138,000-a-year Commons Speaker.

Labour MPs and peers last night rallied behind Michael Martin, denouncing what they see as a "nasty", "sickening" and "pernicious" campaign to get him ousted as the £138,000-a-year Commons Speaker.

Friends of the Glasgow North-East MP are outraged at the viciousness of recent attacks on him, which they say are based on snobbishness and an anti-working class old Tory establishment world view with elements of anti-Scottishness.

They are bracing themselves for more allegations in this weekend's newspapers as rumours multiply at Westminster that his critics are keen for him to announce soon that he will not remain in office for another parliament so that possible replacements can start campaigning.

Mr Martin, 62, who took on the historic Speaker's role in 2000, has come under increasing pressure to quit after being embroiled in the expenses scandal involving disgraced Conservative backbencher Derek Conway and over his use of air miles for family members gained on official business.

At last week's Prime Minister's Questions, one Tory MP was allegedly overheard saying "dead man walking" as Mr Martin took the Speaker's chair.

Yesterday, one senior colleague said: "He is seen as part of the problem and while people have held their tongues in the past, there could be trouble if he tried to stay in the chair for a third parliament."

A Tory front bencher added: "He needs to let it be known pretty quickly that he sees no future for himself in the next parliament. Otherwise the usual channels may have to do their worst yet again."

However, there is no formal mechanism to oust Mr Martin. If the Speaker wants to remain in office, then there is little his critics can do - other than exert pressure.

This has lately come from the pages of the right- wing press. Mr Martin, once erroneously dubbed Gorbals Mick, has been branded a "second-rate Speaker" and his integrity questioned.

Last night Mr Martin's Labour colleagues rallied to his defence. Rosemary McKenna, MP for Cumbernauld, Kilsyth and Kirkintilloch East, said: "It's the most pernicious and snobbish campaign I have seen in my life in politics. It's just awful. People are out to get him."

Former Scotland Office Minister Lord Foulkes said: "People from privileged backgrounds can't believe someone like Michael can do the job with such distinction."

John Robertson, Labour MP for Glasgow North-West, added: "It's become a class war. It's definitely orchestrated. It's coming from the old dyed-in-the-wool Conservatives who are against a working-class boy from Glasgow."