U.S. lawmakers plan for possible "mass casualty" event, proposing a constitutional amendment to replace members quickly and change various lines of succession in a "national crisis"

Members of Congress have put forward various solutions to address the potential chaos a mass casualty event could cause, ranging from a constitutional amendment allowing lawmakers to appoint their own successors to rule changes aimed at preventing violence from altering the balance of power. However, a POLITICO review found that despite numerous proposals since the 2017 mass shooting at a GOP baseball practice, both Republican and Democratic leaders, including key committee chairs, have made little progress in advancing these ideas. This hesitance is largely due to an unwillingness to confront the issue and a general resistance in Congress to changing its rules.

Some lawmakers see this inaction as dangerously shortsighted.

"The number of rounds in one pistol clip could change the balance of power in the House or Senate," said former Rep. Brian Baird (D-Wash.), who began addressing the issue after the September 11, 2001, terrorist attacks, when a hijacked plane came within 20 minutes of crashing into the Capitol.

Lawmakers and their staff face daily threats of political violence. In 2023, the Capitol Police opened 8,008 cases investigating threats against lawmakers, a 100% increase from 2017. The two assassination attempts on former President Donald Trump are stark reminders of the constant danger public officials face.

The lack of a plan for mass casualty events is especially concerning in the House, which has no mechanism for quickly filling unexpected vacancies. A special election, which can take months, is the only way to replace a member. During that time, the House would be forced to operate with fewer members, potentially leaving large parts of the country unrepresented and opening up any congressional action to legal challenges.

This could place significant power in the hands of members who, for example, skip a State of the Union address or a foreign dignitary’s speech only to see their attending colleagues killed in a terrorist attack. Other high-profile events, such as party conventions, caucus retreats, and international trips, are also potential targets.

Another concern is whether slim congressional margins could motivate political violence aimed at shifting party control.

"One of the real problems is that someone with bad intentions could flip a majority for four months, and that’s terrifying," said Rep. Derek Kilmer (D-Wash.), referencing how long it could take to hold special elections rather than making immediate appointments. "We can’t just say, ‘Well, that’ll never happen,’ or, ‘We’ll deal with it when it happens,’ because by the time it happens, it’s already too late."