The head of Facebook’s blockchain project says development of the Libra project will get tougher, but insisted that the departure of seven companies that had originally backed the venture has forced “no change” on the project.

David Marcus, the head of Calibra, told Yahoo Finance in an interview Tuesday that the development of the decentralized blockchain is “absolutely not” in jeopardy after PayPal (PYPL), Visa (V), Mastercard (MA), Stripe, eBay (EBAY), Mercado Pago, and Booking have all decided to leave the project.

“You really have to, as a member, have passion and energy and fortitude to go through this because it’s hard,” Marcus said. “And it’s going to continue being hard. If anything, it’s going to get harder before it gets easier.”

The ambitious project stems from a white paper unveiled in June detailing plans to build a blockchain that will support a “low-volatility” cryptocurrency called Libra. The currency would be backed by short-term government securities and fiat currency, which users would deposit into the reserve when they exchange their money for units of Libra.

Marcus said he “respect[s]” the seven companies’ decisions to leave the project and thanked the companies for having “the courage to look at potentially disrupting themselves.”

“But I also understand that they also have a responsibility to their shareholders and to their stakeholders and they were under a lot of pressure,” Marcus said, adding that companies outside of the formalized Libra Association council will still be able to offer services on the platform.

On Monday, the Libra Association was formally founded in Geneva, Switzerland with the 21 remaining initial members, including Uber (UBER), Lyft (LYFT), Coinbase, Spotify (SPOT), and Vodafone. Facebook (FB) is spearheading Libra’s development (via its subsidiary, Calibra) but has said decisions regarding the blockchain will be made by the association at large.

In addition to announcing its board of directors (which includes Marcus, in addition to representatives from Andreessen Horowitz, Kiva Microfunds, PayU, and Xapo Holdings), the group on Monday announced that over 1,500 “entities” have indicated interest in joining the group.

The association said 180 entities already met the preliminary membership criteria.

Marcus said now that the association is formal, the next steps will be creating finding “more diversity” in its membership. Per the white paper, the goal is to have about 100 members of the association by its target launch in the first half of 2020.

Marcus said regulatory matters have not been behind the seven departures from the project, despite commentary from U.S. Treasury Secretary Steven Mnuchin assuming that “some of the partners got concerned and dropped out” over rules like anti-money laundering standards.

“We’re fleshing out all of the regulatory requirements and oversight required for this to operate but nothing has changed,” Marcus said.

Marcus said the target launch date in the first half of 2020 is “an ambitious timeline that becomes an external forcing function for everyone.” But he reiterated, as he did to lawmakers in testimony earlier this year, that the project will take its time and wait until it gets regulatory approval before launch.

“We’ve learned a great deal from this process,” Marcus said.

Brian Cheung is a reporter covering the banking industry and the intersection of finance and policy for Yahoo Finance. You can follow him on Twitter @bcheungz.

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