Six weeks this summer witnessed the high and low points of Ed Miliband's relationship with Britain's Jewish community.

When he addressed the Labour Friends of Israel annual lunch on June 17, the warmth of his reception reflected his pledge to remain a "friend of Israel", but also his moving description of "the deeply personal journey" he had made to the Jewish state over Passover.

But then came Operation Protective Edge, when Miliband suggested that David Cameron's "silence on the killing of hundreds of innocent Palestinian civilians" was "inexplicable".

The statement on Israel that will be presented to its conference next week sums up the problem. Fleetingly reaffirming its belief that a two-state solution needs a secure Israel, its call for an end to the blockade of Gaza makes no mention of Hamas, tunnels or rockets.

Such one-sided language recalls Miliband's first speech as Labour leader, which attacked Israeli policy in Gaza.

BICOM's director of research, Toby Greene, believes he spent the next three years trying to reassure Jewish voters. Hard electoral calculation required he do so: the Jewish vote could play a key role in Labour's target marginal seats.

But that strategy is now in tatters, the victim of three wider weaknesses which may scupper Miliband's chances next May. First, his support within Labour is intertwined with his political persona as the anti-Blair. Recalling the former prime minister's support for Israel during the Lebanon war in 2006, Miliband will have known instinctively the position he was required to adopt.

Second, the Labour leader's stance on Gaza reflects the soft nature of his party's support. Once Nick Clegg opened the bidding in the anti-Israel auction, Miliband was forced to up the ante. He is reliant on holding the left-of-centre vote which defected to the Lib Dems over Iraq in 2005 but bolted in 2010 with the formation of the coalition.

Third, Miliband is torn between his own soft-left temperament and the more centrist approach he suspects holds the keys to No 10. Shoring up Liberal Democrat defectors may make Labour the largest party, but only by appealing to voters in seats like Finchley and Golders Green and Ilford North can he guarantee a working majority.

When Miliband steps onto the stage at LFI's conference reception, he will be bracing himself for a chillier welcome than he received in June - an indication, perhaps, of the lengthening odds on Downing Street having its first Jewish occupant since Benjamin Disraeli.