Comcast - which owns NBC and Universal Pictures - apparently only plans to go ahead with the bid if a federal judge allows AT&T Inc's planned $85bn acquisition of Time Warner to proceed, with a decision for that expected to come in June.
Under the deal, Disney will also acquire FX Networks, National Geographic Partners, Fox Sports Regional Networks, Fox Networks Group International, Star India and Fox's interests in Hulu, Sky plc, Tata Sky and Endemol Shine Group. That opened the door to Comcast's counteroffer.
Reuters reported that Comcast was in the process of asking investment banks to put in place a bridge financing facility valued as much as $60 billion.
Murdoch agreed to sell US entertainment assets - though not the highly profitable Fox News Channel - to Disney, rejecting a higher offer for those assets from Comcast.
Some analysts believe Comcast would have to suspend its share buyback program entirely if it was able to snatch Fox from Disney's jaws, although its dividend appears safe for now.
Comcast has already made a formal unsolicited $31 billion offer in Europe for Sky satellite-TV business, which is partly controlled by Murdoch. Comcast's stock fell 5.5 percent Tuesday to $30.59 in response to the news.
"Comcast and Disney are likely to view this as the last remaining transformational deal in media".
Comcast Corporation shares were unchanged in premarket trading Tuesday.
Comcast's stock has dropped since then, from around $38 to about $32 now, giving the company a market capitalization of $149 billion.
It could be a bit, however, before any offer is officially submitted, though, as it's said that Comcast isn't looking to make the offer just yet. It is not a solicitation to make any exchange in commodities, securities or other financial instruments.