Schools currently have a statutory duty to assess children within seven weeks of them starting reception class.
A total of 90 baseline assessment schemes, accredited by the Qualifications and Curriculum Authority, are used by schools. The results help to inform teacher practice in the classroom.
Now ministers are due to move to a single assessment to be conducted at the end of reception year, just before children start statutory schooling at age five.
The plans follow Warwick University research which found that teachers want one nationally-comparable assessment to use as evidence for threshold applications and inspections.
QCA advice to ministers is thought to support the proposal. The House of Commons education select committee early-years inquiry also backed the move.
But teachers' unions have pointed out that reception teachers' workload would be doubled if baseline assessment is moved.
Teachers would still have to assess children when they entered reception class, to establish a child's learning needs, and then be forced to repeat the exercise at the end of the year.
The National Union of Teachers fears that an assessment at the end would in effect become a test of how well schools have taught the foundation stage. Reception teachers would then be under the same stress as key stage 1 and 2 teachers to hit targets.
A Department for Education and Skills spokeswoman said ministers were considering the advice from the QCA following consultation.