When junior doctors went on strike in April, Gerard Coyne was there to back them.

He addressed a rally of 500 striking medics in Birmingham City Centre, telling them: “You are the very life blood, keeping the heart of the NHS pumping. Without you, the NHS is nothing.”

Now Mr Coyne, West Midlands Regional Secretary of Unite, finds himself at the heart of Labour’s internal battles. And some people think he could save the party from disaster.

It follows Unite General Secretary Len McCluskey’s announcement that he plans to step down as head of the union, the biggest in the UK, which he has led since 2011.

But he doesn’t want to retire just yet. Mr McCluskey is forcing a leadership contest, to take place in April 2017, in which he will stand again.

If he wins, he’ll have a mandate to lead the union until at least the 2020 General Election.

The bid to tighten his grip on Unite may have something to do with the knowledge that there are people inside the Labour Party who desperately want him gone.

Opponents of Labour leader Jeremy Corbyn hold Mr McCluskey partly responsible for what they see as the party’s woes.

They’ve been counting the days until he goes, and they were privately pushing Mr Coyne as a potential successor long before Mr McCluskey’s recent announcement.

In 2015, Unite backed Mr Corbyn for the party leadership (although Mr McCluskey initially toyed with supporting Andy Burnham).

Unite the Union leader Len McCluskey.
Unite the Union leader Len McCluskey.

And Mr McCluskey was a staunch supporter as Labour MPs manoeuvred to try to convince Mr Corbyn to resign.

When Labour MPs voted for a motion of no confidence in Mr Corbyn in June, Black Country MP Tom Watson , Labour’s Deputy Leader, attempted to end the crisis in the party by encouraging Mr Corbyn to stand down voluntarily and with dignity.

He asked Mr McCluskey to act as an honest broker in the talks. But the discussions collapsed, with Mr Watson saying there was no point continuing because the Labour leader was determined to stay in post.

It emerged that Mr McCluskey had been encouraging Mr Corbyn to stay on. He issued a statement saying: “I made it absolutely clear from the outset of these discussions that Jeremy Corbyn’s resignation as the leader was not on the agenda.”

Some Labour MPs believe that Mr Corbyn had been ready to quit, until his resolve was bolstered by Mr McCluskey and Shadow Chancellor John McDonnell.

It led to a fresh leadership contest, in which Mr Corbyn faced a challenge from Labour MP Owen Smith and won a convincing victory, once again with the support of Unite.

The union even launched a membership drive in the run-up to the contest, encouraging people to sign up to back Mr Corbyn.

Of course, Mr Corbyn’s supporters would no doubt applaud Mr McCluskey’s approach, particularly his support for the Labour leader in the face of attempts by MPs to force him out.

But those MPs who believe Labour is headed for disaster think the Unite leader is letting down his members, who (Labour MPs say) need a Labour government to stand up for working people.

They believe Mr McCluskey is more interested in seeing a “true socialist” party in place than in winning elections and forming a Government.

And they believe Mr Coyne is the candidate to replace him. The West Midlands Regional Secretary has not yet declared his intention to stand, but an announcement is expected soon.

The West Midlands is something of a hotbed of opposition to Mr Corbyn.

Labour First, a group of “moderates”, recently held its annual general meeting (an early 2017 AGM) in Oldbury in the Black Country. Labour First openly states it is campaigning against Momentum, a group which backs Mr Corbyn.

MPs who have expressed support for Labour First over the past two years include John Spellar (Lab Warley), Ian Austin (Lab Dudley North) and Khalid Mahmood (Lab Perry Barr). Mr Watson (Lab West Bromwich East) spoke at the event, in a loyal speech criticising the Lib Dems.

Now, the West Midlands is also at the heart of a battle in a union representing 1.4 million people, which could determine whether “moderates” ever win back control of the Labour Party.