A group of drug companies competing with one another to be among the first to develop coronavirus vaccines are planning to pledge early next week that they will not release any vaccines that do not follow rigorous efficacy and safety standards, according to representatives of three of the companies.

The statement, which has not yet been finalized, is meant to reassure the public that the companies will not seek a premature approval of vaccines under political pressure from the Trump administration. President Trump has pushed for a vaccine to be available by October — just before the presidential election — and a growing number of scientists, regulators and public health experts have expressed concern over what they see as a pattern of political arm-twisting by the Trump administration in its efforts to combat the virus.

The companies’ joint statement was planned for early next week, but it may be released before then after its existence was made public on Friday by The Wall Street Journal. The manufacturers that are said to have signed the letter include Pfizer, Moderna, Johnson & Johnson, GlaxoSmithKline and Sanofi.

The pharmaceutical companies are not the only ones pushing back. Senior regulators at the Food and Drug Administration have been discussing making their own joint public statement about the need to rely on proven science, according to two senior administration officials, a move that would breach their usual reticence as civil servants.