A left-wing activist is to challenge Christine Blower for the leadership of the National Union of Teachers (NUT), TES has learned.

After months of speculation, Ms Blower announced last July that she would seek re-election as the union’s leader, a role she has held since becoming acting general secretary in 2008.

It had been widely expected that Ms Blower would be unopposed in her bid to win another five-year-term.

Although she was an active member of the union’s left-wing Campaign for a Democratic and Fighting Union faction before she became general secretary, Ms Blower has also proved to be a popular figure among members to the right of the NUT’s political spectrum.

But it has emerged that she will be challenged by Martin Powell-Davies, one of the most prominent figures on the left of the union.

Mr Powell-Davies previously stood unsuccessfully for general secretary in 2004, and last year finished third in the NUT national officers elections.

An outspoken supporter of industrial action, he proved to be a thorn in the side of the party’s leadership at last year’s national conference, speaking in favour of bringing forward plans for a national strike in June, in spite of a programme of regional strikes alongside the NASUWT having already been announced. The counter-proposal was voted down by delegates.

Mr Powell-Davies has also campaigned for a national strike over pay, pensions and working conditions to be held this term, but no official announcement has yet been forthcoming from the NUT. More concrete news is expected this week.

In his campaign flyer, Mr Powell-Davies says the NUT and NASUWT has “too often” tended to “hesitate” over escalating their campaign to national strike action.

He has called for an “ongoing calendar of national action”, including a two-day strike, as well as a national work-to-rule to “resist any attempt to worsen conditions”.

Mr Powell-Davies also calls for a doubling of the planning, preparation and assessment (PPA) allowance to 20 per cent of a teacher’s day, as well as the abolition of Ofsted, retirement for teachers at the age of 60 and guaranteed pay progression for all teachers on the main pay-scale.

Mr Powell-Davies requires 10 nominations to secure an election run-off against Ms Blower, which would take place in June.