Close watchers of the vaccine race had already known that Pfizer wouldn’t be able to meet the requirements of the Food and Drug Administration by the end of this month. But Friday’s announcement represents a shift in tone for the company and its leader, who has repeatedly emphasized the month of October in interviews and public appearances.

In doing so, the company had aligned its messaging with that of the president, who has made no secret of his desire for an approved vaccine before the election. He has even singled out the company by name and said he had talked to Dr. Bourla, whom he called a “great guy.”

Some scientists applauded Pfizer’s announcement.

“This is good, really good,” said Dr. Eric Topol, a clinical trial expert at Scripps Research in San Diego who was one of 60 public health officials and others in the medical community who signed a letter to Pfizer urging it not to rush its vaccine.