A source says the Trump Hotel Collection’s proposal would keep the Old Post Office Pavilion exterior and would include a museum gallery. (Jeffrey MacMillan/For Capital Business)

Trump Hotel Collection, the luxury lodging brand that bears the name of the New York real estate magnate, has proposed transforming the historic Old Post Office Pavilion into a nearly 300-room luxury hotel complete with conference meeting space, a spa and museum.

Though listed on the National Register of Historic Places and located on Pennsylvania Avenue between the White House and the Capitol, the Old Post Office has been deemed under-utilized by the government. The General Services Administration began soliciting proposals.to redevelop the property in March, setting a July 20 deadline.

The GSA is not releasing information on submissions, but Ivanka M. Trump, Donald Trump’s daughter and executive vice president of development and acquisitions for the Trump Organization, confirmed that the company is among the respondents.

“The Old Post Office building is an iconic building in Washington, D.C. and a spectacular opportunity for redevelopment,” Ivanka Trump said in an interview. “Preserving the architectural integrity of this great asset should be fundamental to all plans presented to the GSA.”

Ivanka Trump, who previously worked for developer Forest City Ratner, declined to publicly discuss details of her company’s submission, saying she did not want to interfere with the GSA’s decision process.

However, a person familiar with the company’s plans, who asked not to be named because the individual was not authorized to discuss them, said the Trump plans include transforming the property into an “ultra-luxury” hotel with nearly 300 rooms, a large ballroom or conference room, a spa and a museum gallery dedicated to the building’s history leading into the building’s clock tower. The plans retain the building’s exterior facade as well as its original doors, hallways and interior features.

The Trump Hotel Collection already operates luxury hotels in Chicago; New York; Las Vegas; Waikiki, Hawaii; and Panama, where the Trump Ocean Club became the tallest building in Latin America in July. The company plans to open a Toronto hotel later this year.

Trump headlines a pool of development firms and hotel companies, both local and out-of-town, that have proposed redevelopment ideas for the Old Post Office. Organizers of a National Museum of the Jewish People submitted a detailed proposal for a museum of Jewish heritage on the lower levels and a Park Hyatt Hotel above. Local firms the JBG Cos. of Chevy Chase and Monument of the District also made submissions.

This is not the first time the GSA has sought interest from the real estate sector for the building; in 2005 the agency also issued a solicitation and received 20 responses from firms, including Akridge, Carr, JBG, Hines, Loews, Republic Properties and Trammell Crow Residential. The earlier solicitation was later canceled.