The present Labour Party Brexit policy was set by the lay delegates to its annual conference nearly eighteen months ago. That policy is, and always has been, a General Election first then a second referendum.
No other political party, media pressure or individuals have changed that policy, and Labour is the only party to have possessed a consistent stance throughout the last two years.
The Lib Dems supported a second referendum, but then changed their minds on that and became the revoke party.
The ERG/Tory party stated we would leave in March this year, then we would be leaving in October this year and now possibly in January next year. The forgoing chaos for the country was brought about simply because the Tory Party and their paid help in the House of Commons, the DUP, could agree on nothing at all on Brexit among themselves
Therefore, and as stated, Labour has been the only party in Parliament to have maintained a consistent stance on Brexit and that has been due to the decision it's lay members made in 2017.