Fifteen of the party's 26 divisional chiefs called on the party's central leadership to appoint former chief Hj. Ansari Abdullah, instead.
The 15 divisional chiefs are from Tuaran, Batu Sapi, Beluran, Kota Marudu, Semporna, Kalabakan, Kudat, Ranau, Sepanggar, Putatan, Pensiangan, Sipitang, Tenom, Kota Belud and Labuan.
Their action comes just days after its Vice-President Datuk Dr Jeffrey Kitingan, who headed the party's Pensiangan division, quit the party to concentrate on the Borneo Agenda espoused by his newly-formed United Borneo Front.
At a press conference here, the disgruntled group's spokesperson, Anthony Mandiau said the divisions want the central leadership to consider the majority voice of PKR grassroots in Sabah that Ansari should be the State chief. He said the 15 divisions in PKR Sabah, including Labuan, have unanimously pledged their full support and confidence in Ansari.
"We are very disappointed with Thamrin steering the party.
Since his appointment as the party State Liaison Chief for the last one year, the party has been in limbo, with no direction whatsoever.
"He (Thamrin) also failed to address or state the party's stand on several vital issues in Sabah like the problem of customary native land, issuance of native certificate and other things.
"The movement of PKR Sabah under Thamrin has been very slow and no efforts or strategic plans have been made as part of preparations to face the forthcoming 13th General Election, believed to be this year," he said.
Also present were PKR Sabah Communication Director Ronnie Klassen, Democratic Action Party (DAP) Sabah Secretary Dr Edwin Bosi and PAS Sabah Deputy Commissioner 3 Mohd Aminuddin bin Aling.
It is imperative for Thamrin as the State PKR leader to formulate and implement strategies to spearhead the party as the backbone of opposition parties," said Anthony who is also Kota Marudu divisional chief.
"Unfortunately, he has made PKR Sabah an irrelevant coalition partner of Pakatan Rakyat (PR) Sabah. If this persists and is allowed to continue, PKR Sabah may end up in Sabah's political history as a party that failed to live up to the aspirations of the people.
"We will not allow our future generation to suffer due to the incompetence of such a leader," Anthony said, adding that three more divisions would come forward to make their pledge for Ansari to be appointed as the PKR Sabah Liaison Chief.
To illustrate his point, he cited the PKR Libaran Division, which Tamrin heads, as among the non-performing divisions that has a low number of members with no activities carried out by its Wanita wing as well as committee members.
According to him, Thamrin has also failed the party's loyalty test when he disappeared and did not help the election campaign of Pakatan Rakyat (PR) candidate in the Batu Sapi parliamentary by-election in November last year.
"PKR Sabah has been in a disarray for the last one year, and the time has come for us to be focused and steadfast.
"Ansari has commendable education qualification, vast experiences, visionary and very loyal to the struggle of PKR since 1999," Anthony said.
He added that the unanimous pledge and clear intention of the 15 divisions have been made known to party President Dato' Seri Dr. Wan Azizah Wan Ismail via a letter duly signed by them and faxed to her on Tuesday.
He has also stated that the 15 divisions will stay loyal in PKR although Datuk Dr Jeffrey has decided to leave the party and continue his struggle under a non-governmental organisation (NGO).
Anthony said the Central PKR Sec-Gen Saifudin Nasution is expected to chair a meeting with all the divisional heads of PKR Sabah in regard to the appointment of PKR Sabah State Liaison Chief at Atlantis Restaurant at 3pm today (Thursday).
To a question, he said out of 15 divisions, only Kudat and Pensiangan have acting divisional chiefs as their former chiefs including Datuk Dr Jeffrey Kitingan for Pensiangan have left the party.
Although Ansari has lost in several elections including the recent Batu Sapi parliamentary election, Anthony said what they want is the honest leadership of Ansari.
But the PKR Constitution, he said, does not state that the central leadership of the party has to listen to the majority of the people when making a vital decision (in regard to the appointment of PKR State Liaison Chiefs).
He said the party President has the prerogative as to who she feels is the most qualified to be the State chiefs.
But Anthony said he is optimistic that the party President would listen to the majority of the party grassroots in Sabah.