Property tycoon Trump has been battling to construct a $1.5 billion resort in Aberdeenshire for years, and was finally granted permission from the Scottish government to proceed with his plans last November (08).
But locals near the Menie Estate, the location of Trump's latest venture, are furious at the decision, because some are facing possible eviction to make way for the ambitious hotel, housing and golf complex.
Swinton has signed a petition against the resort, joining 15,000 other Scots who are bidding to overturn the government's decision.
She says, "Surely this kind of industrial bullying has been discredited enough. I trust Aberdeenshire Council to know its Highland history and to resist giving in to this attempt at a 21st-century clearance."
George Sorial, a representative for the Trump Organization, has accused Swinton of siding with "extremists" and has urged her to do her research before making further "ill-informed" statements.
Now Trump himself has weighed in on the issue, blasting the actress for her late involvement in the campaign.
He tells TMZ.com, "Where was Tilda Swinton three years ago when everyone else was petitioning? She's a little late in the game don't you think?
"Swinton is a part of a tiny little group of people who are hanging by a thread. Ninety-three per cent of the public in Scotland are in favour of the project. I have all of my permits and approvals and we're going to start construction in three weeks."