Main entrance to the Old Post Office Pavilion on Pennsylvania Ave. NW. (Tracy A. Woodward/THE WASHINGTON POST)

Donald and Ivanka Trump have come to terms with the General Services Administration on a 60-year lease of the Old Post Office Pavilion that will pave the way for their company to turn the building into a 275-room luxury hotel expected to open in late 2015 or early 2016.

GSA officials said the lease now goes before Congress for a 30-day waiting period, though the deal does not require congressional action. Construction could start in the first quarter of 2014.

In an interview, Ivanka Trump, vice president of the Trump Organization, said the family’s hotel “will rival the greatest hotels in the world.”

She said her company planned to complete the deal without other investment partners.

“This is our project. It will be all Trump equity. We have no equity partners. And that makes sense for us, given that our intentions are to hold the asset in the long term. Having the asset without partners allows us to do that. We view this and have always viewed it as a generational asset,” she said.

After winning a competitive process for the building in February of 2012 following a request for proposals for the property, the Trumps worked with the GSA and historic preservation officials on agreements for re-use of the building. The GSA has been working on relocating the building’s existing users.

“Redeveloping the Old Post Office with a private sector partner will save millions of taxpayer dollars while restoring a unique and important historic asset,” said Dan Tangherlini, acting administrator for the GSA, said in a press release.

Trump said that the lease sticks closely to the deal her company originally proposed in response to a request for proposals.

“The deal is exactly what the deal was that we proposed in the RFP,” so the negotiations themselves were not the challenges. The timing challenges were just that the other stakeholders that needed to sign off,” she said.

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