Steven Mnuchin, President-elect Donald Trump’s pick to lead the Treasury, arrives at Trump Tower in New York on Dec. 12. President-elect Donald Trump’s pick to lead the Treasury Department is likely to face a contentious confirmation battle centered on his purchase of a failed subprime mortgage lender that repeatedly has been accused of wrongful foreclosures. The formal vetting process for Steven T. Mnuchin, who served as Trump’s campaign finance chairman and worked at investment bank Goldman Sachs for nearly two decades, has not yet begun.