An eleventh-hour bid has been made to prevent Dumfries House and its contents being sold to a private owner.
The property's contents are due to be sold at auction in July
The SAVE Britain's Heritage Fund has received £7m in donations to keep the historic home and its contents intact.
Completed in 1759, Dumfries House in Cumnock was put up for sale by the Marques of Bute at a price of £6.75m.
The property's contents, which include furniture made by Thomas Chippendale, are due to be auctioned in July and are expected to make a further £12m.
The campaign to save the property was instigated when the National Trust for Scotland failed to reach agreement on the acquisition of the historic home from the owner.
Johnny Bute, 48, who was a Formula One racing driver under the name Johnny Dumfries, first announced his intention to sell Dumfries House three years ago.
He said he wanted to restructure his family's finances and concentrate on his family home - Mount Stuart - on the Isle of Bute in the Firth of Clyde.
To date, leading charities the Art Fund and the Garfield Weston Foundation have both pledged £2m and £1m respectively.
The Monument Trust, founded by the Sainsbury family, has offered £4m towards the campaign.
Despite the donations, the £7m is thought to represent only a quarter of the amount needed to keep both house and contents together.
Fiona Lees, chief executive of East Ayrshire Council, said the local authority firmly supported the campaign.
She said: "Dumfries Estate represents a national treasure in architectural, heritage and environmental terms.
"It has the potential to become a catalyst to assist in the regeneration of the former Coalfield area within which it is located, as well as being a focus for the economic development of Ayrshire in general.
"East Ayrshire Council firmly supports the move to save Dumfries House for the nation and the news that £7m has been pledged is a tremendous development."
Campaigners say that if they are successful in their bid they plan to open Dumfries House to the public as a tourist attraction as well as using the estate for the benefit of the local community.