WASHINGTON (AP) — Metro officials say contractors building the new silver line are behind on some key items, which could lead to further delays for the project.

Metro’s chief of operations, Rob Troup told reporters Monday that contractors agreed to complete a checklist of 33 items before the line opens this summer. But Troup says the contractor and the Metropolitan Washington Airports Authority are behind schedule on about half the items. The airports authority is overseeing construction of the new line, which extends Metro past Tysons Corner and will eventually reach Dulles International Airport.