The transfer has yet to pass the hurdle of a medical, which could prove tricky as Gascoigne has a calf strain, a troublesome hamstring and a possible hernia problem. Should all go well, he could make his Boro debut in Sunday's Coca-Cola Cup final against Chelsea at Wembley.
The 30-year-old Gascoigne was given the hard sell by Merson, who called the former Newcastle and Tottenham midfielder to tell him how his move to the Teesside club from Arsenal had rejuvenated his game and lifted him back into the England team.
Gascoigne, who will miss out on Rangers' attempt to win a 10th successive Scottish Premier title, had previously stalled on the transfer, feeling he was being pushed out by chairman David Murray.
Gascoigne joined Rangers from Lazio in June 1995, but this season has seen him start only 16 games and his dwindling influence, through injury and suspension, may have has persuaded Murray to let him go with two years still remaining on his contract.
Merson has settled well in Gascoigne's native North-east and has provided Boro with much needed quality as they push for promotion to the Premiership. He will be ideal company for Gascoigne as he struggles to make England's World Cup squad. His battle with drink, drugs and gambling has won Merson the respect of his fellow professionals and Gascoigne, who has had his share of personal problems, will empathise with him.
Merson's intervention helped Bryan Robson beat off competition from Premiership strugglers Crystal Palace. "I'm delighted Gazza is joining us," Robson, the Boro manager, said. "He's a great player and our fans will be really excited about watching him play.
"Paul should give us that little extra in midfield, which should help us achieve the ambitions we are setting ourselves."
Gascoigne will join Boro in training today and have his medical "in the next few days". Whether he plays against Chelsea remains to be seen. "I've got to assess Gazza's fitness and see what he's done with Rangers," Robson said.
Gascoigne's advisor, Mel Stein, revealed that leaving Rangers was one of the toughest decisions his client has had to make in his career.
"He is very, very sad to be leaving Rangers. It's an enormous wrench," Stein said. "Paul said to me 'I've left clubs before, but I've never been so sad about leaving a club.' I don't think there will be a problem with his medical. He's probably a bit rusty, probably not quite match fit, although he is available for the Coca-Cola Cup final."
"His England ambitions remain as strong as ever. I'm not saying he wouldn't have been picked for the World Cup if he had stayed at Rangers, but clearly there is going to be a hell of a lot of competitive football in the weeks ahead for him."
More good news for Boro yesterday came from their Italian defender Gianluca Festa. Described by Robson as "a model professional", Festa has signed a new five-year contract.Reuse content