President Donald J. Trump escalated his campaign against political adversaries on Saturday, formally revoking the security clearances of a sweeping list of current and former officials, including former Vice President Kamala Harris, former Secretary of State Hillary Clinton, and former President Joe Biden.

The decision, which also targets members of Mr. Biden’s family, former Secretary of State Antony J. Blinken, and former National Security Adviser Jake Sullivan, was framed by the White House as a critical step to protect national security interests.

In a memorandum issued from his Bedminster, N.J., golf property, Mr. Trump declared, “I have determined that it is no longer in the national interest for the following individuals to access classified information.” The move builds on earlier revocations in February targeting Biden administration figures and extends to vocal critics like former Representative Liz Cheney and national security lawyer Mark Zaid.

The inclusion of Mr. Biden’s relatives has intensified scrutiny, with critics questioning the legal grounding and scope of the action.

The White House defended the decision as a necessary safeguard, but opponents swiftly condemned it as a partisan overreach. “This is an abuse of power masquerading as national security,” said Senator Chris Murphy, Democrat of Connecticut. Historically, former presidents and senior officials retain clearance access to facilitate continuity in times of crisis—a tradition Mr. Trump has now upended.

While the practical effects may be limited—former leaders typically lose formal clearances upon leaving office—the symbolic resonance is profound. Issued amid ongoing tensions with his predecessors, Mr. Trump’s directive underscores a deepening divide in Washington.

As the nation grapples with polarization, this action raises pressing questions about the future of bipartisan trust and the stewardship of America’s secrets.