A backbench Bill banning large stores from opening on Christmas Day is set to become law.
MP Kevan Jones joined protesting shopworkers dressed as Santa
Durham MP Kevan Jones' Christmas Day (Trading) Bill aims to stop 25 December becoming another shopping day and prevent staff from having to work.
Stores currently only have to close if Christmas Day falls on a Sunday.
Members of the Union of Shop, Distributive and Allied Workers (Usdaw) clad in Santa Claus outfits were at Parliament in support of the Bill.
Under the Private Member's Bill, stores larger than 280sq metres would be banned from opening on Christmas Day.
It has already cleared the Lords, and was set to complete its Parliamentary stages on Friday - the last day for backbench business before the end of this Parliamentary session.
Mr Jones said his Bill had cross party backing and support from the main established churches.
He said Parliament must protect the "unique nature" of Christmas.
Some large stores had begun testing the market in recent years and there was a danger of a "domino effect" with others following suit in the face of competitive pressures, he said.
In support of the Bill, 10 Usdaw members arrived at the Houses of Parliament carrying a large banner saying: "Usdaw says Thanks for Protecting Christmas Day."
An Usdaw spokesman said : "This latest development marks an important stage in Usdaw's long-running battle to protect shop workers from being forced to work on Christmas Day.
"Usdaw is hopeful the legislation will be introduced in time for Christmas 2004, allowing staff in the larger stores free to spend time with families and friends on this special day."