Maryland transportation officials have pushed back by five months a major bid deadline for private companies seeking to build and operate a Purple Line, saying the firms requested more time to find cheaper ways to do the $2.45 billion light-rail project.

The March 12 deadline has been pushed back to Aug. 19, said Erin Henson, a spokeswoman for the Maryland Department of Transportation. She said state officials notified the four bidders Friday evening.

Henson said it was too soon to know whether the change will affect the project’s schedule. State transit officials have said they hope to begin construction on the 16-mile line between Prince George’s and Montgomery counties later this year and open it to service in 2020.

The state has delayed the bid deadline once before, after Maryland Gov. Larry Hogan (R) won election in November. The initial January deadline was pushed back to March after state transit officials said they wanted to give the new governor more time to evaluate the proposal championed by his predecessor, Gov. Martin O’Malley (D).

Hogan criticized the project during the gubernatorial race as being too expensive but asked Pete K. Rahn, his nominee for Maryland transportation secretary, to analyze whether it could be done more cheaply. Rahn told The Post in an interview Feb. 12 that he was meeting with bidders to see if they wanted more time and “flexibility” to reduce costs. The state is pursuing a 35-year public-private partnership in which a team of private companies would design, build and operate the line, as well as help finance its construction.