Lucy Allan is aiming to raise thousands of pounds on CrowdJustice, an online crowdfunding platform, so that the Future Fit decision can be challenged in court.
Last week she urged Telford & Wrekin Council to launch a judicial review of the decision to go ahead with the Future Fit plans, which will see Shropshire's main emergency centre based in Shrewsbury and an 'A&E Local' in Telford.
She suggested that a legal challenge could force more compromise over the proposals and said that if the council does not go ahead with it she would look at other means to do so.
Ms Allan said she had been in discussion with solicitors who are experts in public law, who can mount a challenge on behalf of a group of residents, who qualify for legal aid.
A message posted on the fundraising page says: "If NHS management get their way, in 10 years time Telford will have a population of 202,000 people, but no A&E and no Women & Children's Centre.
"We cannot let this happen. The evidence shows that over 50 people per night use A&E at Princess Royal. But managers have told ministers only five patients attend per night.
"Telford has poorer health outcomes, pockets of significant deprivation, and increasing health inequalities. Our health needs are greater and funding must follow need.
"We will use the money raised through this page to instruct solicitors with experience in challenging reconfiguration decisions, to review the Future Fit process and get a barrister's specialist opinion on whether there are grounds to issue a judicial review.
"We need £5,000 for solicitors to undertake this initial work.
"If you can make a contribution and share this page, you will have played your part in securing the future of Telford's Princess Royal Hospital."
The terms of an 'A&E Local' have not yet been fully defined, although NHS England has suggested it would only be open for "core hours".
The CrowdJustice campaign has already raised more than £140.
The money needs to be raised by November 27.
Pledges can be made at crowdjustice.com/case/save-telfords-hospital-services-stop-future-fit