While senators were aiming for an early morning vote on their in-the-works fiscal deal, calculations from congressional number-crunchers quickly raised questions about how House Republicans would take it. 

In short, according to rough calculations forwarded by a source close to the talks, the proposal would include $620 billion in new tax hikes and $15 billion in net spending cuts. 

That kind of lopsided ratio could turn off House conservatives, presuming the bill clears the Senate. 

One Republican predicted House leaders may only be able to attract 70 Republicans in the chamber. 

The tax hikes would mostly come from an increase on families making more than $450,000. 

The value of net cuts, though, was held back because of the sheer amount of spending in the proposal. Long-term jobless benefits, for example, would be extended for a year, at a cost of $30 billion. 

Fox News’ Ed Henry and Chad Pergram contributed to this report.