WASHINGTON (AP) — Narrowly beating a midnight deadline, Congress voted Monday to renew an expiring ban on plastic firearms that can evade airport detection machines. But Republicans blocked an effort to toughen the restrictions — the latest defeat for gun-control forces in the year since the grade school massacre in Newtown, Conn.

President Barack Obama signed the law before midnight, using an auto pen as he traveled to Africa for ceremonies honoring the late South African President Nelson Mandela. The device Obama used to sign the bill has been used for the signatures of traveling presidents since the administration of President George W. Bush.