The lawyer told reporters at Islamabad High Court that the new party's members will comprise the former high-ups, MNAs and MPAs of the Imran-led party.
He went on to add that the new outfit will have the complete support of the 'corridors of power', making a reference to the powerful quarters of the country.
Marwat was further quoted by private TV channels as saying that the PTI activists are also being asked to extend support to the former Khyber Pakhtunkhwa chief minister in his pursuit.
In a major blow to the PTI earlier this month, Khattak announced to step down as the party's chief of the Khyber Pakhtunkhwa chapter.
The development came hours after the former KP CM and another PTI leader Asad Qaiser went 'missing', and were reported to be at a safe house.
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Making the announcement in a video statement, the veteran politician said he reached his decision after "consulting friends".
Brushing aside the 'propaganda' on electronic media, former PTI stalwart said he made his decision after a careful consideration of the situation.
Khattak also said he would decide his future course of action after consulting "friends and party workers" further.
According to a recent analysis, Imran's support in KP was intact only until he had Khattak’s support, but the latter had been in contact with a number of people, including Jahangir Tareen.
Adil Shahzeb had said during the programme Khabar Say Aagay that the ex-KP CM would take some two dozen workers of the party with him.
Defections in the former ruling party began in the wake of the May 9 unrest that involved the targeting of security and government installations.