Former Labour MP Frank Field is set to make an announcement “on his political future” on Friday.
The chairman of the Work and Pensions Select Committee sits as an independent after resigning the Labour whip last August citing anti-Semitism and "nastiness" in the party.
A source suggested he would not be standing down, sparking speculation he could be set to formally join another party.
Mr Field, 77, has been MP for Birkenhead in Merseyside since 1979 and is one of the longest-serving MPs in the Commons.
As the Work and Pensions committee chairman, Mr Field has been a vocal critic of the Government's Universal Credit reforms and often speaks out in the Commons on rising poverty and inequality levels.
He is close friends with Heidi Allen who quit the Tories to join Change UK.
The pair went on an anti-austerity tour together at the beginning of this year.
When he left Labour almost a year ago, the Birkenhead MP said that under Mr Corbyn Labour was “increasingly seen as a racist” party.
He also cited the culture of “nastiness and intimidation” within the party as the reasons for his departure.
But he said at the time he would remain a member of the party and stand for Labour again at the next election.
His announcement suggests this prospect is now unlikely.
Mr Field, who was asked to "think the unthinkable" on welfare reform by Tony Blair is often seen as being on the right of the Labour Party.
His pro- Brexit stance has angered members in his constituency Labour Party - and he lost a motion of no confidence in his local party after he voted with the Government in a knife-edge Brexit vote.
