A politician who pledged to "not rest" until Salisbury had a bypass insists he has not gone back on his word.
John Glen MP said in a 2010 manifesto his city "badly needs a bypass", but he has recently backed spending £2bn on a nearby tunnel alongside Stonehenge.
He said it remained the case that he would continue seeking improvements.
Talk of a bypass was reported last week as Highways England considers ways to alleviate congestion around the ancient monument 10 miles (16km) from the city.
"I have always said that I will not rest from seeking improvements to Salisbury's roads infrastructure," the Conservative MP for Salisbury said.
"However, we need to be clear that the A303 improvements that are currently proposed are not just about Salisbury but are part of a much larger national infrastructure project."
The 1.8-mile (2.9km) Stonehenge tunnel is the preferred option but some archaeologists argue it could damage the World Heritage site.
Mr Glen added it would be "impossible to combine this significant national infrastructure work" with a local project in Salisbury.
"To attempt to do so would risk imperilling the whole scheme," he said.
"Reducing congestion and improving air quality remains a key priority. However, Stonehenge is almost 10 miles from Salisbury and it is not in my power to redefine national infrastructure projects and mould them to my wider priorities for the city."