In their letter, the senators said Icahn should be re-classified by the Trump administration as a special government employee, making him subject to ethics requirements.
When Trump announced in December that Icahn would be a special adviser, Trump made clear he would "not be serving as a federal employee or a Special Government Employee and will not have any specific duties."
The letter also includes over a dozen questions about Icahn's ties to the administration, including whether he has received waivers from ethics requirements, and whether he has divested from some of his financial holdings.
This article was provided by Reuters.