BOSTON—Boston’s troubled MBTA is once again under the national spotlight — this time with the Trump administration threatening to choke off federal dollars unless Mayor Michelle Wu and General Manager Phil Eng take immediate action to make the system safer.

Transportation Secretary Sean Duffy fired off a blistering letter Friday demanding the MBTA deliver a full safety plan within two weeks. The feds want details on how Boston is tackling fare evasion, violent assaults, and rampant vagrancy, citing recent horror stories: a 63-year-old woman shoved off a Roxbury bus and left injured on the pavement, and a rider swinging his belt like a weapon near Harvard Square.

Duffy accused Boston and Chicago of embracing “soft-on-crime” policies that let “deranged criminals repeatedly terrorize public spaces” — warning that cashless bail and weak enforcement are putting riders at risk. South Station, long a hotspot for complaints about drugs and disorder, was singled out as a place where conditions must improve.

The threat is clear: comply, or lose millions in federal transit funds that keep the MBTA limping along. For a system already plagued by runaway costs, broken trains, and delayed fixes, losing Washington’s money could be catastrophic.

Mayor Wu, who has styled Boston as “the safest city in America,” now faces another political showdown with Trump’s team — one that could decide whether commuters ride in safety or chaos.