What significant personnel changes are occurring in federal agencies and what are the reasons behind them?

The Department of Homeland Security is preparing to fire hundreds of senior leaders this week, according to three sources who told NBC News. This strategic move aims to eliminate personnel deemed misaligned with the administration's goals and objectives. Meanwhile, the top official at the Social Security Administration resigned over the weekend following a disagreement with Elon Musk's Department of Government Efficiency (DOGE). Sources indicate she refused DOGE's request to access sensitive government records, highlighting tensions between agency leadership and new efficiency initiatives.