The level of support is astounding, especially 2 1/2 years before the Democratic Party hosts its nominating convention. The total represents more than 20 percent of the 253 Democrats in the House and Senate. It is also more than half of the lawmaker endorsements Clinton received in 2008.

The list of 56 includes liberals and centrists who represent states from California to Ohio to New Hampshire.

The Hill contacted congressional Democrats to ask whether they would back Clinton in the 2016 Democratic primary if she runs. Most offices did not respond to requests for comment, or declined to comment.

A Senate Democratic aide said, “You want us to comment on whether the senator supports a candidate who hasn’t declared, in a race that isn’t underway and in which no one is running?”