David Martin, who was a Scottish Labour MEP for 35 years until last night when Labour only polled 9.3 per cent of the vote in Scotland, revealed he had tried to shift Scottish Labour's Brexit position to make it distinct from that of the UK Labour Party.
But as a result of being unable to do so Scottish Labour has "suffered" - sliding to fifth place in Scotland.
Speaking on BBC Radio Scotland, Mr Martin was asked if Richard Leonard needed to consider his position as leader in light of the European election results. Prior to the election Mr Leonard had said he was "responsible" for the party's performance at the ballot box.
But Mr Martin said: "I think Richard is, in relative terms, only a short time into this position [as leader]. He was swept along with the national position. It was very difficult for Scottish Labour... I tried and Richard tried but it was very difficult for us to have a distinct position... so we suffered along with the UK position
"I think it's too early to judge his leadership... many of the issues he's focusing on, on public service and fairness at work do resonate with Scottish people but are not being heard because of the constitutional debate."
Senior Labour figures have already piled pressure on Jeremy Corbyn to shift the party’s Brexit policy firmly in favour of a second referendum in the light of the European election result.
Asked if Mr Corbyn's was to blame, Mr Martin said: "I understand the position that Jeremy Corbyn tried to take. As leader of one of the two major parties and with a referendum which said we should leave the EU, he felt an obligation to try and deliver that.
"But it's become cleat it's impossible to deliver what the people have asked for. And he's been stuck in this limbo of knowing the damage a hard Brexit would do to the country and trying to respect the outcome of the referendum."
He added: "I'm not sure his views on Europe are as well known as people think. I don't think he's fundamentally anti-European. It's true historically, when in his words, he saw it as a "neo-liberal project" he was anti-Europe but I think he's moved and he understands that much of what Labour wants to achieve can only be achieved with cooperation with our European neighbours."
Mr Martin who said he would now pursue "academic interests" admitted he was "extremely disappointed" not to be returned as an MEP and said Labour's message just "did not get across".
"It became a polarised debate. The public decided this was a rerun of the referendum, and in a referendum it's binary choices and you have to take sides and we failed to be perceived as having taken a side.
"I think we have to reflect carefully- it's easy right after an election to come out with hard lines but we need a shift of position, to reestablish ourselves as the pro-European party.
"I think, ironically, the Labour Party position has become much more important than it was until now, as I fear with the success of the Brexit Party a lot of Conservative backbenchers who were lukewarm on a hard Brexit will be panicked and depending on the outcome of the Prime Minister election in the Conservative Party we will see a headlong rush to get out on the 31st of October, regardless.
"But they still need numbers in the House of Commons and that's where the Labour Party becomes absolutely vital and I hope we will stand firm and say no hard Brexit, we need a second referendum and we will go back to the people."