A new 7000-series train prepares to depart from the Pentagon Metro Station in April. (Matt McClain/The Washington Post)

THE NATIONAL Transportation Safety Board issued a safety recommendation for Metro on Monday on electrical short-circuiting that may have factored into January’s deadly smoke accident. Meanwhile, many in Congress are threatening to shortchange the transit authority. That would be an understandable but counterproductive response to the agency’s missteps. Cutting Metro’s funding would only worsen the system’s problems.

Though the NTSB will not complete its investigation until early next year, its report Monday urged immediate repairs to cable connectors, saying a failure to comply could lead to further loss of life. The NTSB found that, throughout the Metro network, numerous electrical cable connectors lack protective sleeves designed to prevent overheating mishaps like the one that took place in January. Other connectors have been installed with mismatching parts. Perhaps most worrying, even after the accident, Metro failed to use the sealing sleeves as it performed emergency repairs. All of this again throws into doubt Metro’s claim to have inculcated a culture of safety since a 2009 Red Line accident that killed nine people.

Metro’s construction manual includes diagrams of cable connectors with the protective sleeves, but the book labels them desirable rather than mandatory. Right now, Metro does not have a system for ensuring uniformity among its connectors, even though such uniformity would best ensure rider safety, the NTSB said. The NTSB report urges Metro to fix this flaw.

Metro has promised to adopt all of the NTSB’s most recent recommendations. Focusing first on areas most prone to water contamination, Metro plans to bring all 8,347 cable connectors up to snuff for safety and to revise its construction manual so future connectors are required to have sleeves. Certainly, this process is essential — but it should have begun long ago. A culture of safety preempts disaster, rather than just responds to it.

Republicans in Congress may deem budget reductions an appropriate punishment for Metro’s lapses, or they may be using those lapses as an excuse to defund mass transit. Either way, those who would be punished the most would not be Metro officials but the riding public, including thousands of congressional aides and federal employees, and the Washington area, which depends on a viable transit system. To the protests of the regional delegation, a House committee voted to cut Metro’s allocation by a third. This would reduce the federal contribution to $100 million per year, reneging midway through a 10-year commitment to fund Metro at an annual level of $150 million. Congress ought to keep its end of a bargain that local governments have honored, even as it insists on improvements in operation. In the long run, inadequate funding will compromise safety as well as service.