A mortgage salesman who worked for a bank that extended $16 million in loans to former Trump campaign manager Paul Manafort testified Friday that he was “uncomfortable” about the transaction because the bank’s chief executive was trying to get a job in the Trump administration.

Over the past two weeks, during Mr. Manafort’s trial on tax and bank fraud charges, prosecutors have presented evidence to support their allegations he earned some $60 million through political-consulting work in Ukraine in the early 2010s, used some of the money to pay for a life of luxury and failed to report that money as income.

Prosecutors also have called witnesses who testified that Mr. Manafort was losing clients and income by 2014 and that by 2015 and 2016 was making fraudulent loan applications to U.S. banks.

Mr. Manafort’s trial is the first to emerge from special counsel Robert Mueller’s investigation into the 2016 presidential election. Mr. Manafort has pleaded not guilty.

On Friday, Dennis Raico, a former salesman from Federal Savings Bank, who received immunity to testify, said the bank’s CEO, Steve Calk, was personally involved in approving two loans to Mr. Manafort on properties in Brooklyn and in the Hamptons, which he said was an unusual role for Mr. Calk.