Big U.S. banks are set on getting Congress this year to loosen or eliminate the Volcker rule against using depositors’ funds for speculative bets on the bank’s own account, a test case of whether Wall Street can flex its muscle in Washington again. In interviews over the past several weeks, half a dozen industry lobbyists said they began meeting with legislative staff after the U.S. election in November to discuss matters including a rollback of Volcker, part of the Dodd-Frank financial reform that Congress enacted after the financial crisis and bank bailouts.