His former colleagues,Stirling Griff and Rebekha Sharkie,learned of his decision on Sunday,with Senator Griff saying it was"disappointing"and a"self-marketing move".
"He has been running his own race for a while now,but his actions have effectively removed a powerful voting bloc that has achieved a remarkable amount for South Australia,"Senator Griff said.
Those close to Senator Patrick say he will probably"re-brand"ahead of the next federal election and his exit from the party was to give him the best opportunity to secure 14 per cent of the SA vote to gain a Senate quota.
Loading
But his move potentially hands Senator Griff more power to negotiate with the Morrison government,with the Coalition requiring any three of the five crossbench senators – One Nation's Pauline Hanson and Malcolm Roberts,Senator Griff,Senator Patrick and Tasmanian Jacqui Lambie – to pass legislation.
Several Senate figures expect Senator Patrick to form a tighter alliance and potential voting bloc with Senator Lambie,with whom he has a"very close working relationship",sources say.
A spokeswoman for Senator Lambie said on Monday she would continue to work closely with both South Australians.