Western Australia is emerging as the next political battlefront for the banking sector as Commonwealth Bank steps up a new drive to slash costs across its national operations.The country's largest bank is preparing to axe 150 mortgage processing roles in Brisbane over the next 12 months, with the functions to be reallocated to back office centres in Sydney.The decision follows a move earlier this month to cut 54 assistant managers at Bankwest branches after CBA decided to rein in trading hours across the network.Since it acquired Bankwest at the height of the Global Financial Crisis in 2008, special state legislation passed by the former Barnett Government has restrained CBA's ability to cull branches and centralise back-office functions outside of WA.But those restrictions - embodied in the Bank of Western Australia Amendment Act (2012) - are due to expire at the end of September.That will clear a path for CBA chief Ian Narev to close branches and potentially relocate administrative functions to the back office centres in other states.However, recently elected Labor premier Mark McGowan is coming under intense political pressure from the Finance Sector Union and several government backbenchers to renew the existing arrangements for another five years.Bankwest operates 66 branches in WA that employ about 1000 people. Another 2500 people, including the senior executive team headed by Rowan Munchenberg, are employed at Bankwest's Murray Street headquarters in the Perth CBD.The prospect of deep job cuts at Bankwest looms as political poison for McGowan, who won the March state election in a landslide on a promise to restore employment opportunities in Perth and regional WA.FSU state secretary Di Marshall is banking on McGowan to save her members' jobs and has stepped up the union's campaign to retain the legislated conditions on CBA's ownership. "We are actively campaigning because we want to make sure that the current requirements for no branch closures are retained," she told Banking Day."My biggest worry is that many administrative roles at Bankwest Place in Murray Street will eventually be shifted to CBA's new technology centre in Redfern in Sydney."Banking Day understands that McGowan discussed matters relating to the Bankwest legislation with a delegation from the union last month.Given the willingness, in recent months, of Australian governments to confront the major banks with controversial public policy, few in the industry should be surprised if the WA government decides to put another brake on the country's largest financial institution.The ailing WA economy has also imposed pressure on Narev to improve returns from the struggling Bankwest business.According to disclosures in CBA's half year accounts, Bankwest posted a 12 per cent decline in earnings for the six months to the end December.Much of the underperformance was attributable to sharp increases in provisioning for impaired loans made to home borrowers and credit card customers.With activity in the WA mining sector yet to bottom out and unemployment in the state still the worst in the nation, CBA is likely to focus on trying to reduce costs to lift bottom line contributions from