Nearly two-thirds of primary school leaders want to scrap the controversial new baseline tests for four- and five-year-olds starting school this autumn, new research suggests.
And only 16 per cent believe the Reception Baseline Assessment (RBA) would be a good use of teaching time, according to a YouGov poll for campaign group More Than A Score.
Last month the government confirmed that the new baseline assessment for Reception children will become statutory in September this year.
The tests should have been introduced in September 2020, but the start date was postponed due to the Covid crisis.
The survey of 234 senior primary school leaders in England, weighted by region, found that a majority (64 per cent) believe the RBA should not go ahead this year.
And nearly two-thirds (63 per cent) agreed that the impact of the Covid crisis on pre-school experiences will "render any data produced from the tests useless as a baseline measure", More Than A Score said.
The campaign group is now calling for heads, teachers, early years specialists and academics to sign an open letter to education secretary Gavin Williamson, asking for the tests to be cancelled as part of the government's Covid recovery plan.
"A child-focused recovery plan must start with our very youngest pupils," the letter says.
"It must give them the time and space to settle in to school, not be subjected to tests in English and maths.
"In any year, the information obtained from such young children would be unreliable and unhelpful to teachers and parents. In a year when nursery experiences have been at best disrupted and at worst non-existent, its collection is a pointless waste of teachers' time."
Chris Dyson, headteacher at Parklands Primary School in Leeds, said: "The first few weeks of school are so important for our young learners. The last thing they need is for that critical settling-in period to be disrupted by an irrelevant data-gathering operation.
"My teachers want to spend that time making sure their pupils are happy and comfortable and starting their learning journey with confidence. I trust them to do this job by assessing pupils' needs through careful observation, not a formal test in English and maths."
Nancy Stewart, from More Than A Score, said: "The coming school year is not the time to subject any primary school children to formal government tests. The focus must be on pupils' emotional wellbeing and mental health and that starts with the very youngest children."
The Department for Education said the baseline assessment will account for any impact on pupils' educational experiences up to this point.
It added that the RBA will use materials familiar to most children of this age, and should be administered it in a way that does not put pressure on pupils.
The assessment will help create a fairer accountability system for schools, the department said, and will reduce the number of assessments at primary level overall.