The losing contractor of a bid for a half-billion dollar project to build part of Honolulu’s planned rail line plans to sue and has asked the Federal Transit Administration to step in.

Bombardier Transportation USA Inc. said Monday it has asked the FTA to review the disqualification of its rail proposal by the city and the decision by a state hearings officer to uphold the denial.

The $574 million contract to build 80 rail cars and provide power to a system control center went to Ansaldo Honolulu in January.

Bombardier says it is asking the FTA to terminate the contract award. It also plans to file a lawsuit in Hawaii Circuit Court claiming the city did not follow procurement law.