The Portuguese giants want to land Morelos and are claimed to have already thrashed out personal terms with the Colombia international.
They are now seeking to agree a fee with Rangers as they look to take Morelos to the Estadio do Dragao this summer.
Porto are now claimed to have offered Rangers a fee of €12m for Morelos, while the deal would also contain a sell-on clause.
In addition to the €12m, Rangers would also earn 20 per cent from any fee Porto bank from selling Morelos in the future.
The striker helped Rangers to win the Scottish Premiership title last season and the Gers have Champions League football on the agenda for the upcoming season.
Morelos though is suggested to want to make the move to Porto.
Rangers have already signed a forward this summer in the shape of Fashion Sakala, but it is unclear if Steven Gerrard will feel he still has enough attacking options if Morelos goes.