Although the FIA published a provisional 22-race schedule after its most recent World Motor Sport Council meeting in September, it is understood that F1 chiefs are preparing a fresh overhaul.
Sources say that neither New Jersey nor Mexico will feature in the final version - with both tracks needing more time to get their venues ready.
Although New Jersey has long been in doubt, Mexico was close to getting fully prepared but it is understood that efforts to build a new pits and paddock complex meant it will not feature until 2015.
The absence of those races will reduce the season to 20 races, which teams have long viewed as the maximum number of events they can comfortably cope with.
As well as the changes to those venues, some consideration is also being given to reshuffling the start of the season so that the second race in Malaysia is moved forward a week.
Doing so would make it a double-header with Australia - which would be cheaper for teams than having it back-to-back with Bahrain as it currently is.
No final decision on this matter has yet been taken, however.
Korean organisers are also still in discussion with F1 supremo Bernie Ecclestone about its scheduled April slot after China.
If no deal can be reached on fees, then one scenario that has not been completely ruled out is for India to make a potential return - even though it had been expected to be absent from the 2014 schedule prior to getting its race back the following year.
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