The beleaguered transit system in the Northeast may receive a boost from one of the most ambitious entrepreneurs in the world.

Elon Musk tweeted Thursday that The Boring Co. received "verbal" government approval to begin building an underground Hyperloop, saying it would take 29 minutes to go from New York to Washington, D.C.

"Just received verbal govt approval for The Boring Company to build an underground NY-Phil-Balt-DC Hyperloop," Musk said.

@elonmusk tweet.

The proposed Hyperloop would connect the city centers of New York, Philadelphia, Baltimore and Washington, as Musk tweeted in a follow-up.

@elonmusk tweet.

While Musk did not say the source of his verbal approval, a White House spokesperson told CNBC that Musk has spoken to the Trump administration before.

"We have had promising conversations to date, are committed to transformative infrastructure projects, and believe our greatest solutions have often come from the ingenuity and drive of the private sector," the White House spokesperson said.

Musk cautioned that there is "still a lot of work needed to receive formal approval," even while he is optimistic that a regulatory green light will be given quickly.

@elonmusk tweet.

An Amtrak ride on the Northeast Regional line from Washington to New York currently takes three hours and 20 minutes, according to the passenger railroad company's website. Deteriorating rail infrastructure in the Northeast has been highlighted recently by emergency repairs at New York's Pennsylvania Station after a series of derailments. Penn Station is owned and operated by Amtrak.



At the International Space Station Research and Development Conference in Washington on Wednesday, Musk said another one of his plans, to dig tunnels under Los Angeles, is a "low stress activity" because "everyone expects it to fail." Musk has said previously he has had "promising conversations" with Los Angeles Mayor Eric Garcetti about moving forward with the project, but has yet to receive a permit from the city.

Musk plans to start digging the New York to Washington route at the same time as the Los Angeles urban congestion project. Asked whether Texas might receive a Hyperloop system, Musk tweeted "for sure" before enumerating on his plans.

@elonmusk tweet.

A Los Angeles to San Francisco route would be the third Hyperloop project proposed by Musk, as he continues to plot connections between major U.S. cities.

Philadelphia city government spokesman Mike Dunn, told CNBC that Musk has not contacted Philadelphia officials about his plan.

"We do not know what he means when he says he received 'government approval,'" Dunn said. "There are numerous hurdles for this unproven 'hyperloop' technology before it can become reality."

The press secretary for New York City Mayor Bill De Blasio responded to Musk's tweet, saying "this is news to City Hall."

@EricFPhillips tweet.

Eric Phillips said he has "no clue" what Musk's reference to "verbal approval" means.

A New York City community board chairman also denied knowledge of a plan to tunnel on the eastern seaboard.

"This is my first time hearing this; none of this has come to the community boards," Anthony Notaro Jr. said, chair of Community Board 1 in Manhattan.

Mayor's offices in Washington and Baltimore were not immediately available for comment.

— Kelly Song contributed to this report.