A leading charity for disabled people has said thousands are "deeply worried about losing their financial lifeline" due to benefit changes.
The Government has announced that private companies Atos and Capita have been given the contracts to run a new work-capability check for disabled people.
The assessments, which will see Personal Independence Payments replace Disability Living Allowance, will start next year. Up to two million people will need to be assessed for PIP.
Scope is among the charities to question their fitness to do the job properly, after criticism of Atos' handling of unemployment benefit assessments.
Richard Hawkes, Chief Executive of Scope, said:
"Disabled people are incredibly anxious and afraid that the switch from DLA to PIP is just an excuse to cut the support they need.
"The decision about which private company will run the assessment is of little significance to the thousands of disabled people who are just deeply worried about losing their financial lifeline."
"Just this week the Government and Atos, the contractor who carries out its fitness for work test, have come under a great deal of criticism about how this assessment is being delivered to disabled people.
"Yet in less than a year from now, disabled people could have to go through two deeply flawed assessments in the same month to get the essential financial support they need to live their lives."
Mr Hawkes said the new assessment process for PIP is "deeply flawed".
"It doesn’t take into account all the barriers that disabled people face in daily life," he said.
"And the Government, who designed this assessment, doesn’t appear to be learning from the mistakes they have made through the fitness to work test."
Scope wants ministers to publish the descriptors and activities assessors will use to determine eligibility for PIP.
It also called for new outreach workers to follow up on individual cases where there is a concern about a person who has not responded to the news that their DLA will be coming to an end.
The charity said disabled people who are ineligible for PIP but who are found through their assessment to be facing considerable barriers should be "signposted to services that can help them".
The Government said DLA is "outdated" and PIP "will better reflect today’s understanding of disability" with recipients choosing to spend it in a way that suits them best.