The Chelsea Supporters' Trust is understood to be sympathetic to public health concerns over staging the Champions League final at Wembley, with Portugal now looking the more likely option.
A meeting between tournament organisers UEFA and the British Government on Monday to discuss moving the match to the London venue from Istanbul ended without an agreement being reached.
The Government's decision last Friday to place Turkey on its high-risk 'red list' for international travel meant supporters of the finalists, Chelsea and Manchester City, were ordered not to attend and would require the players and club staff to quarantine in a Government-approved hotel for 10 days on their return.
Transport Secretary Grant Shapps said on Friday the Government was "very open" to discussing staging the final, but it is understood the sticking point on Monday concerned the number of non-essential personnel – sponsors, delegates and broadcasters – who UEFA sought quarantine-free entry to the country for.
Chelsea Supporters' Trust accepts public health must come first and that the easing of coronavirus restrictions must be the first priority, and that anything which could jeopardise that should be avoided.
Portugal has now emerged as the most likely venue unless UEFA and the British Government can reach an agreement in further talks on Tuesday.
It is on the Government's new 'green list' of countries that can be visited without the requirement to quarantine on return, which would make it a more viable option than Turkey.
It is understood UEFA would like to have reached a final decision by the end of Tuesday, though it may not be made public until later in the week.
Porto is understood to be the venue being put forward by the Portuguese federation.
If UEFA does move the match there, it will be the second year in a row that Portugal has staged the Champions League final, after Lisbon did so last August.