After a visit to Haas' North Carolina headquarters, Auto Motor und Sport correspondent Michael Schmidt says the Gunther Steiner-led team's "plan A" is to race next year.
Schmidt said Steiner, who has worked with Jaguar and Red Bull, is now rapidly building a workforce, with many experienced F1 people showing interest because Haas can offer new challenges and high-ranking positions.
"There are many interested parties," a source said, "but we can only hire people when we know who our engine partner is."
The front-runner is Ferrari, who are also keen to supply a lot of other components to Haas.
Mercedes has already ruled itself out of the running to fill Haas' needs.
"We can only offer engines and transmission," said team chairman Niki Lauda.
The Haas car will almost certainly be built by Dallara.
Schmidt reports: "A 200-strong staff is under construction. In September, the factory in Mooresville will be ready."
At the same time, Haas is also looking for somewhere to base itself in England, the report added.