One of the two other bidders SpaceX or Sierra Nevada Corp is expected to obtain a smaller contract as a second source.
NASA, which spends nearly $71 million for each one-way trip for astronauts to space using the Russian Space Shuttle, is planning for NextGen spacecraft that suits its needs.
"There is a growing consensus among space experts that Boeing is likely to emerge as the big winner to develop and operate the nation's replacement for the space-shuttle fleet which was retired in 2011," the report said.
According to a Boeing spokeswoman, the company has demonstrated that "the method and order in which we design and test has been successful."
Till date, California-based SpaceX was being seen as the leading competitor because of its success in reliably transporting cargo to the orbiting international laboratory.
But Boeing now appears to have become the favourite because it has met earlier deadlines within the budget, the report noted.