Labour power plays simmer under surface
The political focus of attention has been on cabinet splits recently, not on shadow cabinet unease.
Backed by nearly 60% of Labour members and supporters and presiding over a growing party, Jeremy Corbyn's position should be unassailable.
It isn't, of course, because overwhelmingly his MPs still don't believe he will lead Labour to success at the general election.
The expected wave of criticism after the English local elections was in the end a mere trickle, as a lacklustre performance in many areas was overshadowed by victory in London, and in some councils in southern England.
The need to refocus on the referendum also stemmed the flow of denunciations.
Talk of leadership challenges hasn't evaporated, though.
Mr Corbyn has moved swiftly following the local elections to deprive critics of a stick with which to beat him - failure to campaign with any vigour to stay in the EU.
He has featured in a glossy pro-EU Labour leaflet and delivered speeches around the country on the "progressive case" for continued membership.
Sotto voce critics in the shadow cabinet believe now isn't the time to try to depose him, and that many new members attracted to Labour by his anti-austerity platform would see this as a parliamentary coup and rally to his defence.
Some senior shadow cabinet members had been keen to commission polling to see if new members were becoming any more sceptical about Corbyn's leadership - and last month the Times obliged.
A YouGov survey suggested that nearly two-thirds of party members would either definitely or probably vote for him again - confirming the cautious approach taken by some of his critics to an early attempt to oust him.
So the assumption is that, if challenged, Mr Corbyn would get enough MPs to re-nominate him and enough party members would support him - so why strengthen his position?
That's not to say others outside the shadow cabinet won't move to try to undermine him.
They fear Mr Corbyn's supporters will change Labour's rules at this autumn's annual conference to make a challenge more difficult, and to make it easier to nominate another left-winger should he stand down before the next election.
But at the grass-roots level there has been plenty of activity in the undergrowth.
Self-styled moderates say activists from Momentum - the organisation set up to keep alive the spirit of the Corbyn leadership campaign - tend to be concentrated in certain areas.
There have been battles to win delegates to Labour's annual conference and some on the centre and right are confident they will win enough positions to see off any rule changes beneficial to the leadership.
That would give them longer to think and plan a leadership challenge.
Meanwhile, Mr Corbyn has been doing what he can to avoid further open division.
Jeremy Corbyn is nothing if not consistent. In the mid-1980s he campaigned against what he saw as a "witch hunt" against members of the Militant Tendency, as Neil Kinnock denounced them and had them purged from his party.
These members, though, were indeed "witches" in the sense that they actually belonged to a different political party, the Revolutionary Socialist League - a Trotskyite organisation which aimed (with some success) to infiltrate Labour.
Mr Corbyn was never a member of any such group, but he always favoured keeping the door on the left of Labour's broad church open.
More than that - unlike some of his close allies - he isn't a natural knife-wielder.
When he was selected as the candidate for Islington North, his local Labour party was bitterly divided.
What helped gain him the nomination wasn't a purge of those to his right, it was the departure of "self-purging" members who left to join the new SDP.
But Mr Corbyn to this day believes that it was the division of the left - rather than Labour's pro-CND, anti-EU, pro-nationalisation manifesto - which cost his party the subsequent 1983 election and he isn't keen to cause a formal split again.
So while he hasn't compromised on his views - hence the review of his party's defence policy - he has signalled he wants to lead a broad movement from the left rather than a narrower but purer sect.
By putting the mainstream chief whip Rosie Winterton in charge of Labour's response to the boundary reviews - which some on the left wanted to use as a means of deselecting MPs whose views they didn't like - he has signalled he isn't ready to launch an all-out assault on internal critics.
This despite calls from delegates at the GMB union conference this week to unseat disloyal members of the parliamentary party.
He also spoke recently at the annual conference of Progress, the modernising group in the party set up by, among others, Peter Mandelson - an organisation which, according to shadow chancellor John McDonnell has a "hard-right" agenda.
Even Mr Corbyn's much-trailed "revenge reshuffle" at the start of the year left in place shadow foreign secretary Hilary Benn, who had publicly dissented from his line on Syria.
That was nonetheless seen as a sign of weakness, not magnanimity, as Benn's departure would probably have been followed by others.
There is little doubt, however, Mr Corbyn has a greater interest in defending those to his left from expulsion.
During the leadership contest last summer, various people suspected of not sharing Labour's aims and values were weeded out of participating.
But those who suffered most from what was a relatively modest political purge were members, or recent members, of the Green Party.
It was fairly easy to establish if they had previously stood as candidates against Labour.
But many Trotskyist groupings don't often stand candidates against official Labour representatives, and relatively few - with some high-profile exceptions - were stopped from signing up as supporters and voting for the man who became party leader.
Mr Corbyn certainly wouldn't favour throwing out those who might have to come to his aid in another contest.
Nonetheless, beneath the surface, Labour's HQ-based Compliance Unit has diligently gone about its work of implementing and overseeing adherence to the party's rules - much to the chagrin, for example, of Trotskyite group Socialist Appeal.
They have circulated a draft motion to supporters in Labour Party branches which states:
"This branch notes that there has been a wave of expulsions across the country of Jeremy supporters and socialist activists... carried through by the shadowy and unaccountable Compliance Unit.
"We call for the abolition of the Compliance Unit, which is acting in the manner of a vigilante as a law unto itself."
Note that they say the unit is "a law unto itself" - that is, this is not being done at the beck and call of the leader.
But what has bolstered the spirits of some of Mr Corbyn's internal opponents has been his response to the recent spate of allegations of anti-Semitism among a small number of party members.
He was initially criticised for acting too slowly but in the end, defended the use of the party machinery to suspend, investigate, and ultimately expel members who were alleged to have made anti-Semitic pronouncements - long-standing ally Ken Livingstone among them.
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The row has made it likely that the Compliance Unit will, if anything, be beefed up and not abolished.
And all this, in turn, is beginning - just beginning - to draw criticism from the left.
The Trotskyist Socialist Worker opined recently: "It's essential to defend the right of socialists to criticise Israel and oppose Zionism.
"There's a real danger that, in their seemingly endless adjustments to pressure from the right, Mr Corbyn - and especially John McDonnell - may lose sight of this."
And a Labour-supporting contributor to the Morning Star - once the organ of the Communist Party - called for the Labour leadership to do more to face down its critics and make clear: "Anti-Zionism has nothing to do with anti-Semitism."
Those on the left are also pushing for the rules in selecting Labour mayoral candidates to be brought in to line with the rules for selecting a Labour leader - giving newer members a say.
There will be disappointment if the leadership isn't able to bring this about.
The hope of some long-standing Labour members and MPs is that many of the newer members from the far left get disillusioned with either Mr Corbyn or with what the party machine is apparently doing to him and simply clear off, leaving behind those on the soft-left who will genuinely worry whether he is the right person to lead Labour to victory.
They take heart from that recent Times poll which suggested that while around two-thirds of members would back Mr Corbyn now, fewer than half (45%) regarded him as competent. With more time, they hope more people will come to the view that his leadership is a lost cause.
But that's for the future. While some MPs report little activity at election time from the more recent members there is little evidence to suggest these armchair radicals won't still be in the driving seat when the next leadership contest comes.