SERVICE AT the highest levels of the United States government demands a certain instinctive sensitivity to right and wrong when it comes to ethics. So much can happen belowdecks that a Cabinet member or president must set high standards and expect that subordinates will follow the example. This is why the latest disclosures about the Clinton Foundation’s donors raise new concerns about Hillary Clinton’s presidential quest.

The questionable transactions involving the foundation and Bill Clinton’s big speaking paychecks offer fresh evidence of how the Clintons skate close to the edge of propriety. According to a lengthy account published Friday by the New York Times, Bill Clinton accompanied a Canadian mining executive, Frank Giustra, to Kazakhstan in 2005, after which Mr. Giustra acquired valuable Kazakh uranium assets. Mr. Giustra donated millions of dollars to the Clinton Foundation. The mining company merged and expanded, and it became known as Uranium One. It bought uranium exploration properties in the United States, and ownership was partially sold to a subsidiary of the Russian state atomic energy agency.

When the Russians sought to expand their holdings to 51 percent of the company, it required approval of the U.S. government, including the State Department, when Ms. Clinton was secretary of state. The transaction was approved in 2010. More donations to the Clinton Foundation — millions of dollars — flowed from people connected to Uranium One. The same month the sale went through, the former president gave a talk in Moscow sponsored by an investment bank for $500,000. The investment bank was promoting stock in Uranium One. Though there is no evidence of a quid pro quo, on the merits the deal was bad for U.S. interests: Vladi­mir Putin can now boast of control of more than a fifth of U.S. uranium reserves.

The Clintons have sought to do good works with their foundation, but this is not about the works. It is about the fundraising, both for the charity and for the Clintons’ personal benefit. Besides the Uranium One money, millions more dollars have been contributed by foreign governments and interests with a stake in State Department decisions, or in a future president. Bill Clinton, The Post reported, has raked in close to $100 million in speaking fees between 2001 and 2013, a staggering sum that far exceeds the self-marketing of any other president.

The Clintons promised to be transparent about donations to the foundation while Ms. Clinton was in office. However, the Times said the contributions of some connected to the Uranium One deal were not disclosed. The newspaper unearthed them in Canadian tax records. This lapse is exactly the sleight-of-hand that creates suspicion. It was unnecessary and leads to the question: What were the Clintons hiding?

The murky Clinton milieu of donations here and speaking engagements there, a mixture of power, influence and money, of interests commingled and borders blurred is the heavy baggage that comes with Ms. Clinton’s presidential candidacy. There may not be illegality, but there are legitimate doubts about her judgment. The Clintons have long been haunted by criticism of their ethical behavior and appear to think these latest reports can be brushed off as just another storm of partisanship. “Innuendo,” they say. “Utterly baseless.” Such responses do not reflect a proper sensitivity to propriety — which is the problem.