But the HHS will be setting up at least part of the exchanges in all but 17 states. Republican governors, adamant about not helping to implement any part of ObamaCare, have refused to set up exchanges on their own.
"I really think that it is going to be of little to no consequence to the average consumer," Cohen said of the difference between state and federal exchanges.
It makes a big difference, though, for technical and budgetary purposes.
The agency asked Congress on Wednesday for an extra $1.5 billion to implement the federal exchange — money it's unlikely to receive, given the fate of past requests.
Cohen would not say how the implementation effort would be affected if Congress doesn't come through with the additional funds.
He said, however, that the HHS is making good progress on the massive logistical and technological undertaking of setting up the federal exchange.
The department cleared a "significant milestone" April 1, when it opened up the federal exchange to begin receiving applications from insurance companies who might want to sell plans on the exchange, Cohen said.
He said roughly 900 insurers filed information with the health department, and the communication went smoothly.
At least one state, Connecticut, has also been able to interact with the federal government's data hub, Cohen told reporters after the hearing.
The technology infrastructure is one of the most difficult parts of establishing a federal exchange.
The exchange will be tasked with processing applications from people who want to buy insurance and determining whether they're eligible for Medicaid or a subsidy to buy private coverage. That task will require the exchange to communicate instantly with networks at a range of both federal and state agencies.
Exchanges will also verify that insurance plans meet certain criteria and comply with new federal regulations.