A think tank founded by the wife and son of Sen. Bernie Sanders (I-Vt.) will shut down by the end of May to avoid any “appearance of impropriety” during the senator’s race for the presidency, said Sanders’ wife and chief campaign adviser Jane Sanders.

The progressive Sanders Institute in Vermont has already stopped accepting donations.

“I’m going to be very active” in the campaign, and “it’s just too mushy — it could become too mushy,” Jane Sanders told The New York Times. “We wanted to safeguard it.”

Immediately ending donations was the most important step, she said, because “nobody should think that they’re giving money to an organization ... that gains them access or favor to anybody else and anybody running for office,” she told The Associated Press.

It “just seemd the responsible thing to do,” she added.

The public policy group had already begun drawing concerns about a lack of transparency and blurred lines linking politics, family and money.

Jane Sanders said the board acted in late February at the urging of their son, David Driscoll, the executive director of the institute, who previously worked as an executive at Burton Snowboards and Nike, according to the Times. The institute had raised $730,000 and Driscoll was collecting a salary of about $100,000.

The senator has no role in the institute, which was launched after his last campaign for the presidency ended in 2016. His wife said the institute may start up again if Sanders drops his bid for the job.

Sanders — and Donald Trump — criticized the nonprofit Clinton Foundation during the last campaign, saying it was a secret path to buying political access and influence.

New York Attorney General Letitia James is suing the Trump Foundation for $2.8 million in restitution and seeking an order banning Trump and his three oldest children from running any charities in New York for 10 years. James charged in a court filing Thursday that Trump misappropriated funds from the charity to help his presidential campaign. The foundation was shut down late last year.

“Our petition detailed a shocking pattern of illegality involving the Trump Foundation — including unlawful coordination with the Trump presidential campaign, repeated and willful self-dealing, and much more,” then-Attorney General Barbara Underwood said in a statement after the Trump Foundation was shuttered. “This amounted to the Trump Foundation functioning as little more than a checkbook to serve Mr. Trump’s business and political interests.”