“The key here is to make sure that any campaign-finance fund is not being used as a slush fund for personal use, or for donors to curry favor with a candidate, or, in this case, the president,” Senator Catherine Cortez Masto told me Wednesday afternoon. Hours later, the first-term senator from Nevada would introduce the Inaugural Committee Transparency Act of 2019—legislation intended to increase oversight and public disclosure of money spent by presidential inaugural committees. “As a former attorney general, as well as a candidate at the state level, there are certain requirements as a candidate surrounding transparency around donations,” she continued. “It is common sense that there is transparency and accountability around donations that come into any type of campaign.”

Cortez Masto’s legislation comes at a fraught moment. As Robert Mueller’s investigation into possible collusion between Donald Trump’s campaign and Russia appears to near its conclusion, a new front of investigative scrutiny is homing in on Trump’s inaugural committee. It remains unclear, after all, how Trump’s inaugural raised $107 million—twice the amount that Barack Obama hauled in 2009—or why about $40 million was publicly unaccounted for. Rick Gates, a top inaugural aide and member of Trump’s inner circle, has long since become a Mueller cooperating witness. Last year, partly based on the recorded conversations seized by federal agents from Michael Cohen, the Southern District of New York launched a criminal investigation into how Trump's inaugural committee spent its record funds. In December, The Wall Street Journal and The New York Times reported that prosecutors were investigating whether foreign donors from nations, such as Saudi Arabia and Qatar, funneled money to the committee in order to influence U.S. policy. Earlier this month, the committee received a subpoena from the S.D.N.Y. requesting documents related to spending and donors, as well as documents related to a wealthy donor who had once registered as a foreign agent.

Soon afterward, I reported on a series of concerns raised by Stephanie Winston Wolkoff, an event producer and close friend of First Lady Melania Trump, who held a senior role planning the inauguration. In one e-mail from the time that I reviewed, a Trump Organization employee sent the inaugural committee an estimate to rent a ballroom at the Trump Hotel for eight days. The price she quoted was a staggering $3.6 million, inclusive of the food and beverage minimum. Wolkoff articulated her concern, writing in an e-mail to First Daughter Ivanka Trump and Gates: “These events are in PE’s [the president-elect’s] honor at his hotel and one of them is for family and close friends. Please take into consideration that when this is audited it will become public knowledge.” (A spokesperson for Ivanka’s lawyer told me she passed on the inquiry to a hotel official and said only that any resulting discussions should be at a “fair market rate.”)

Last week, ProPublica and WNYC reported that the inaugural committee paid the Trump International Hotel a rate of $175,000 per day for event space. Earlier this year, The New York Times noted that, in total, the hotel was paid more than $1.5 million in inaugural funds. In addition to concerns about payments made to the Trump Organization, there was concern about how organizers were using donations. According to the two people familiar with the matter, Gates approached a couple of individuals working on the inauguration and asked if they would be willing to be paid directly for their work by a donor, rather than by the inaugural committee. They had received more donations than they’d initially anticipated, Gates told these people. Skirting the usual payment route could allow the inaugural committee to avoid reporting the full amount raised from donors. (A lawyer for Gates did not respond to a request for comment.)