Unite: Ian Allinson is third candidate to enter leadership contest
A third candidate has entered the race to be the next leader of Unite, the UK's largest union.
Ian Allinson said he was launching a "grass-roots socialist challenge" to incumbent Len McCluskey and Gerard Coyne, who is also standing.
Mr Allinson, who has worked at Fujitsu for 25 years, said Mr McCluskey was an establishment figure offering "more of the same" rather than radical change.
Unite needs "continuity" at a volatile political time, Mr McCluskey has said.
Mr McCluskey, a key ally of Labour leader Jeremy Corbyn and one of the most powerful figures in the union movement, said last month he would stand down in April before the end of his term, triggering a contest for control of the union.
It had been thought that it would be a straight fight between him and Mr Coyne, Unite's secretary in the West Midlands, who has suggested the union has become too focused on national party politics rather than the interests of its members.
But Mr Allinson's entry into the race - assuming he secures enough nominations from union branches to stand - means Mr McCluskey could face a challenge from the left as well as the right.
The official said he was putting himself forward for election on a platform of increasing workers' powers and participation in the workplace.
"Whatever the result, this campaign will force key issues on to the agenda and bring together those within Unite who want something better than more of the same," he wrote in a blog post on his website.
"Members don't want the clock turning back with Coyne, but neither can we keep waiting for effective resistance from McCluskey.
"I don't have the resources of the establishment candidates. If you want to see a grass-roots socialist challenge then don't just sit back and wait."
Mr Allinson accused Mr McCluskey of "backsliding" on immigration after the Unite leader told the Guardian he supported some curbs on freedom of movement after the UK's exit from the EU to address the "concerns of working people".
The newspaper reported him as saying "workers have always done best when the labour supply is controlled and communities are stable".
"That's why I have called for new safeguards to stop companies cutting costs by slashing workers' wages and transforming a race-to-the-bottom culture in a rate-for-the-job society," he said.
Mr McCluskey, who launched his official campaign on Friday, said protecting jobs and workers' rights in the run-up to Brexit and its aftermath would be his priority as well as campaigning against the worst excesses of the so-called "gig economy".
"Unite will be in the forefront of legal and political campaigns to end the abuses of the flexible labour market," he said.
Meanwhile, Labour's deputy leader Tom Watson has urged Unite members to vote in the forthcoming election. He told the BBC: "It is a golden rule for Labour politicians never to interfere in union elections but [Unite members] have a big choice to make.
"British workers have had a terrible decade when it comes to pay and conditions and they will want to know the person leading the biggest union is totally focused on their interests. I say to Unite members: Make sure you use your vote - it's a vital election and very often people can win elections like these on a very low turnout."
He added: "The general secretary has a great influence on politics - Len McCluskey is close personal friend of Jeremy Corbyn - members can help change the course of history if they decide to vote."