The Government's new reading test for six-year-olds could face a boycott from teachers.
The National Union of Teachers is expected to warn at its annual conference next month that the check is "unnecessary and inappropriate".
The union is due to discuss a motion calling for a campaign against the test, including a ballot for a boycott if the results are used in league tables.
Ministers announced plans for the test at the end of last year. It is based on phonics, a system that focuses on sounds rather than whole words.