The News revealed on Sunday the Blues have been monitoring the progress of the centre-back – as they look to replace the outgoing Hayden Carter.
After impressing with the Robins, it was clear to see why he was on Danny Cowley’s radar due to his stellar performances and expiring contract.
However, it’s understood the 25-year-old has penned a new two-year-deal with the National League side - keeping him at Moss Lane until June 2024.
The right-footed centre-half has made 41 appearances this term in all competitions, while scoring three goals and registering nine clean sheets.
But not all aspirations of a deal are lost for Pompey, as Phil Parkinson may be looking to protect his asset by tying him down.
It’s makes their route to securing a deal for Mullarkey trickier, however, with Cowley having to decide if he believes it’s worth shelling out a fee for the player.
Similar to what Pompey may do with Marcus Harness, Altrincham could be looking to cash in on their prized possession – and can only do so by agreeing fresh terms.
This was due to the fact he was available for a free transfer at the end of the campaign.
The heart of defence is certainly an area Pompey are looking to improve this summer, alongside striking and right-back additions.
With loanees returning to their parent clubs and contracts expiring, Cowley has another rebuilding job on his hands.
But with the Fratton chief plotting next season’s promotion push, perhaps he won’t be too disheartened if he misses out on the ex-Crewe man’s services.
It’s understood Mullarkey is one of a long list of potential centre-backs the Blues are casting an eye over, as they look to find the perfect fit for the position.
Indeed, the ex-Lincoln boss still hasn’t given up hope in bringing Carter back to the club, following the impression he made on loan from Blackburn last season.
Cowley has made it clear he wants the 22-year-old to return to PO4 after shining in 22 appearances on loan over the second half of the campaign.
Pompey had an option on Raggett relating to achieving Championship promotion. That means a new deal will have to negotiated, though both player and club have stated they are keen to come to an agreement.