Jim Murphy is under increasing pressure to clarify speculation over his future as an MP.
The Glasgow politician was re-selected as his party's candidate for East Renfrewshire in 2013 - before he was elected Sottish Labour leader last month.
He has given a "cast iron" guarantee that he will stand to be an MSP in the next Holyrood elections in 2016.
But there has been speculation that he could stand down from Westminster at May's general election and take a "year out" of either chamber before leading Labour's Holyrood elections campaign.
Following claims he would continue as an MP, a Scottish Labour source said: "As it stands he's the candidate and he has been for some time. If anything changes, his constituents will be the first to know."
The SNP and the Conservatives accused Mr Murphy of short-changing voters.
Kirsten Oswald, the SNP's candidate in East Renfrewshire seat, said: "After weeks of dodging the issue, Jim Murphy's intentions in May are still as clear as mud - with just over three months to go until voters go to the polls, Mr Murphy is still leaving open the option of not standing in his East Renfrewshire seat.
"Local voters deserve some real clarity from Jim Murphy as a matter of urgency."
Conservative Candidate Dr David Montgomery said: "East Renfrewshire needs a full-time MP, not someone with one foot out the door."
Last month Mr Murphy told the BBC's Sunday Politics Scotland programme: "I've given a commitment that I'll be in the Scottish Parliament in 2016 and Labour's candidate for first minister in 2016.
"I'd like to be there sooner than that and in terms of how we do that and what we do, of course I'll let my constituents know first and my constituency party know first.
"But there's a cast-iron guarantee to be a candidate in 2016 at those elections, if not before."
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