British Prime Minister Keir Starmer is facing political pressure and calls for resignation ahead of a parliamentary address over his handling of Peter Mandelson’s appointment as U.S. ambassador.

Mandelson was previously dismissed after concerns about his links to Jeffrey Epstein, and it has now emerged he failed a security vetting process before being appointed.

Starmer has said he was not informed of the failed vetting and has called that failure “unforgivable,” leading to the dismissal of a senior Foreign Office official.

Opposition parties have accused him of mismanagement and misleading Parliament, arguing the situation has damaged trust and national security, Reuters has reported.

Starmer is expected to outline the facts to lawmakers as scrutiny of the affair intensifies.