WASHINGTON — The Justice Department said on Monday that it would deploy more than 500 people in 28 states on Tuesday to monitor Election Day practices and guard against intimidation and disruptions.

The number is a sharp decrease from the 2012 presidential election, when the Justice Department had more than 780 personnel in place on Election Day at the close of what was a much less tumultuous campaign.

Officials placed blame for the shrinking federal presence on a 2013 Supreme Court ruling that limited their ability under the Voting Rights Act to deploy observers in jurisdictions — mainly in the South — with a history of voting discrimination.

In announcing the assignment of monitors and observers, Attorney General Loretta Lynch said, “We will continue to have a robust election monitors program in place on Election Day.” She said the personnel “will perform these duties impartially, with one goal in mind: to see to it that every eligible voter can participate in our elections to the full extent that federal law provides.”