The in-demand Doyle was left out of Preston’s squad for the 1-1 draw with Ipswich at the weekend.
Pompey, Bolton and Bradford are among the clubs interested in the 28-year-old’s services for the remainder of the campaign.
The Blues are, of course, at a disadvantage considering they operate in League Two, with Doyle presently at Championship level.
For that reason, Paul Cook has been scouring for an alternative – and Proctor fits the bill.
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Ironically, the 24-year-old plays for Bolton, who need to move him out in order to recruit Doyle.
The Trotters are operating under a 23-man squad embargo and departures are required in order to land the former Chesterfield man.
Pompey have harboured doubts over winning the pursuit for Doyle since the middle of last week, forcing them to cast their eye elsewhere as a Plan B.
It is understood Proctor has been identified as that back-up striking arrival and Bolton are willing to do business.
Proctor has endured a disappointing first season at the Macron Stadium following his summer arrival from Bradford.
The target man impressed during a 21-game spell at Valley Parade in the second half of last term, netting six times.
He helped Phil Parkinson’s side reach the League One play-offs. When Parkinson left for Bolton in the summer, he returned to snap-up Proctor.
The former Preston trainee has also seen service with Crawley and Fleetwood, while was a popular figure during his Bradford spell.
– NEIL ALLEN