The chance of the healthcare bill being ready before the summer recess appears to be diminishing as a group of 40 fiscally conservative House Democrats has objected to some key proposals.
The group signed a letter which states they would not support a legislation that did not include provisions for more significant cost cuts so the reform is "deficit neutral."
They also expressed their opposition to forcing small businesses to participate in a new system.
"We cannot support a bill that further exacerbates the challenges faced by small businesses," the group wrote in a letter addressed to House Speaker Nancy Pelosi and House Majority Leader Steny Hoyer.
In the meantime, Congress has published new figures which suggest a healthcare reform bill being worked on by Senate Democrats – which includes a public insurance option and requires employers to cover workers – would cost $611 billion over 10 years.
That is much less than previous estimates from the Congressional Budget Office which put the price tag at $1.6 trillion during the same period.
The planned reform is intended to ensure universal access to healthcare, while lowering costs and improving efficiency.
The project has already been under fire from congressional Republicans who object to a government-run insurance option which they say would be anti-competitive and drive private insurers out of business.