More than 50 interviews with Democratic leaders revealed a party struggling to decide what it believes in, what issues to prioritize and how to confront an aggressive right-wing administration.

On a call with Senator Chuck Schumer, the minority leader, six Democratic governors pushed him to slow down the confirmation of President Trump’s nominees and to do more to block his agenda.

The number of arrests there was uncertain. Illinois officials, including the governor, said they had not been given advance notice.