Mr. Earnest declined to say whether the president had considered attending the march himself or considered sending Vice President Joseph R. Biden, or to detail the conversations that led to the decision not to do so. But he cited scheduling and security concerns as playing a part.
“The security requirements around a presidential visit, or even a vice-presidential visit are onerous,” Mr. Earnest said, noting that security would have had to secure a large outdoor area, potentially making it harder for other people to attend. “It would have been very difficult to do so without significantly impacting the ability of common citizens to participate.”