Plans for a tunnel taking traffic away from Stonehenge are likely to be scrapped within days.
Winterbourne Stoke's bypass is also threatened
The BBC has learned the government believes the tunnel's cost of £510m is too expensive.
Transport correspondent Paul Clifton said an announcement was due next week which will "almost certainly spell the end of the tunnel".
He said Transport Secretary Ruth Kelly would announce another review of the options, the 10th such review to date.
ALTERNATIVES TO THE TUNNEL
A northern route - which would have a junction with the A360 then go south of Larkhill and rejoin A303 at the Countess roundabout at Amesbury. It would involve a cut-and-cover tunnel
A southern route - which would have a junction with the A360 then go south of Stonehenge before rejoining the A303
A cut-and-cover tunnel - like the first tunnel scheme - but closer to the surface than a bored tunnel
A partial solution - which would include closing the A344 at its junction with the A303 and offer options for the end of the Winterbourne Stoke bypass
English Heritage has refused to comment on the story until the government makes an official announcement.
A Department of Transport spokesperson would only say: "An announcement will be made in due course".
The 1.3 mile (2.09km) tunnel was recommended after a public inquiry in 2004 but was put on hold by the Department for Transport (DfT) when its costs rose to £510m.
The DfT insisted on re-examining some of the options the public inquiry ruled out.
Four options to protect the World Heritage site and provide a bypass for the nearby village of Winterbourne Stoke had previously been unveiled by the Highways Agency in February 2006.
They included a "cut and cover" tunnel, which is cheaper than a deep-bore passage and involves creating a shallow channel and covering it with a roof and a bypass to the north or south and changes to the Countess Roundabout.
News the tunnel is now unlikely to be built has a knock-on effect for the people of Winterbourne Stoke which has the A303 as its main street and had been promised a bypass as part of the wider plan.
Councillor Ian West, who lives in the village, said: "We should be challenging them now to disconnect the two objects because Winterbourne Stoke is still suffering from over 30,000 vehicles a day thundering through it.
"We went through the public inquiry and there were no contentious issues on the line so what we want now is it disconnected then let's do Winterbourne Stoke and they can argue about Stonehenge for another century if they wish."
To date the total amount spent on the A303 Stonehenge Improvement from the time the scheme entered the roads programme in the late 1990s is £19m.
The cost of the public inquiry which was held in 2004 was £3m.