Better Shrewsbury Transport (BeST) said that losses suffered by the Conservative Party in Shrewsbury – including Shropshire Council leader Peter Nutting in his Copthorne division – were illustrative of the lack of support for the planned North West Relief Road (NWRR).
The £87m project has been seen as one of the major reasons behind Mr Nutting's defeat – he has been a vocal advocate of the plan, arguing it is best for the town and securing millions in funding to carry it out.
The 6.9 kilometre highway would complete the Shrewsbury ring road, joining up Churncote Roundabout to the west with the Ellesmere Road Roundabout to the north.
Mike Streetly, a spokesperson for BeST, said: "On Thursday, Shropshire Conservatives suffered their worst result since the unitary authority was set up. Whilst elsewhere in the country the Conservatives increased their share of the vote, in Shropshire it went down, particularly in Shrewsbury.
"It is clear that many voters have lost confidence in the Conservative’s vision for the county. In Copthorne, we saw the North West Road’s biggest cheerleader, Peter Nutting, lose his seat in a shock defeat by a Liberal Democrat challenger who put opposition to the project at the heart of his campaign.
"Across Shrewsbury, more than two out of three of votes went to parties who campaigned against the North West Road as a solution to the town’s air pollution and congestion issues.
"As a result, Shrewsbury’s electoral map has now changed significantly with gains for the Liberal Democrats, Greens and Labour and the possibility of a new Green Party mayor for the town.
"It is impossible not to read this as a pushback against the North West Road plans. We will watch Shrewsbury Town Council’s future vote on this issue with interest."
Conservative cabinet member Dean Carroll, who was re-elected to his Battlefield seat on Saturday, said that he believed the relief road issue had cost his former leader his job.
However, he said he would continue to back the project.
He said: "He made a brave decision to press ahead with the North West Relief Road, knowing it was right for the people of Shrewsbury – and the whole central part of Shropshire.
"It is in the right interests of the people of Shrewsbury as a whole and that has cost him his seat and I really feel for him. He has delivered what we have been trying to do for decades and successive councils have failed to do."
Last Friday saw the deadline for comments on the planning application for the road closed after being extended for a week to give more people a chance to comment.
BeST said that there are currently 2,526 objections and 183 supporting comments on the council’s planning portal.
Mr Streetly added: "Looking at the election results and the overwhelming number of objections to the planning application together, it is clear that there is now no mandate for the road. Voters have shown that they want a solution to Shrewsbury’s traffic problems that is fit for the 21st Century. Shropshire Conservatives need to take stock and listen to the message the electorate has sent them. We’re encouraged by recent statements from acting leader Steve Charmley about listening to opponents to the road."