Many MPs, on the right and left of the party, were incensed by Ms Harman's decision earlier this year to send her son to a selective grammar school, and they now want retribution.
Rightly, they see moves to drop this year's shadow cabinet elections as an attempt to save Ms Harman from a humiliating defeat in the Parliamentary Labour Party's shadow cabinet ballot which is traditionally staged at the beginning of each Commons year, in October or November.
The timetable for that ballot is due to be fixed this week and will be announced at the weekly meeting of the parliamentary party on 17 July.
Anticipating a leadership- inspired ambush, and an amendment that could have stopped this year's ballot on the grounds that it would create a diversion in the run-up to the general election, more than a hundred MPs have warned that they will oppose such a ploy.
The feeling of backbench frustration has been increased by Mr Blair's decision to go for a referendum on Scottish devolution, and by the denial of leadership support for a full, 26 per cent pay increase for backbench MPs this week.
But it is entirely possible that even if Ms Harman were ousted in a shadow cabinet ballot this autumn, Mr Blair could reinstate her as a member of his team - as John Smith did when she was rejected by the parliamentary party when he was leader.
Andrew Mackinlay, MP for Thurrock, and a leading organiser of the backbench revolt, insisted yesterday that the move was not aimed at Ms Harman.
He said the MPs were "jealous" to guard their last remaining power to hold the party leadership to account.
Altogether, 110 MPs had given assurances that they would attend next week's parliamentary party meeting to make sure the timetable went through unamended. "There were strong reasons for believing there were some important people in the party who were trying to prevent the elections from proceeding," Mr Mackinlay said.
Tony Banks, left-wing MP for Newham north-west, told BBC1's Breakfast with Frost: "It is probably the only occasion when we can exercise some democratic rights ourselves. At least it gives us a bit of power and a bit of say as to who is going to be in the team."
The shadow Chancellor, Gordon Brown, told the Sky News Sunday programme that there was no proposal to abandon the elections at the moment. But he said that could change if there was an early general election.
"If there was to be an election in October or November it would be something of a distraction, but there again I suppose that the shadow cabinet elections would not take place," said Mr Brown.
However, John Reid, the party's defence spokesman - who first raised the prospect of dropping the elections at a parliamentary party meeting
in January - said they now should be scrapped for this year.
"Our sole aim should be the defeat of the Conservatives, not the defeat of shadow cabinet members," he said.Reuse content