McGregor stars in Moulin Rouge with Nicole Kidman
The actors union Equity is to meet with its members' agents to get them on their side in an escalating dispute over rights for bonus payments.
Many household names - including Ewan McGregor - have pledged their support to the campaign, which threatens to bring the UK film industry to a standstill.
"I am tired of making producers and distributors rich while I and my fellow actors are exploited," the Star Wars and Moulin Rouge actor said in a message to Equity offering his support for the campaign.
A host of other actors including Simon Callow, Ricky Tomlinson and Caroline Quentin also added their support.
Equity is pushing to renegotiate a contract with the Producers' Alliance for Cinema and Television (PACT) over rights for bonus payments.
In the UK, actors are paid a flat advance for future broadcasts of films, video and DVD sales and other uses.
They get nothing extra, no matter how successful a film is.
Toward the end of August PACT offered to introduce a system of payments linked to a film's use.
But Equity is not happy that performers would actually see any extra money in the near future and rejected the offer triggering a final consultation process leading to a possible strike.
This begins on Tuesday with a meeting with actors' agents.
Equity spokesman Martin Brown said: "It's very important that the agents are behind our dispute and its crucial that they understand the issues here."
Then, on Sunday, every member of Equity is invited to an open meeting in London to discuss the issues.
The following Tuesday Equity's elected council will meet and decide whether to issue the instruction to its members to strike.