The Oversight Committee, like many committees in Congress, has a long history of working with federal whistle-blowers regardless of which party is in charge. Though some come forward publicly, most provide information or leak documents anonymously, helping to lead to investigations and, sometimes, hearings. “It’s entirely proper, and it’s really the point of what the Oversight Committee does,” says former Representative Tom Davis of Virginia, a Republican who headed the panel during the mid-2000s. 

…Members from both parties interact privately with whistle-blowers, but under a long-standing agreement within the committee, those who want to make on-the-record testimony must agree to be questioned by Democrats and Republicans alike.

Lawmakers conduct investigations and interact with whistle-blowers even when they don’t have the majority. But they have less power to act on information, because they cannot, on their own, issue subpoenas or call hearings. …The committee was receiving about three or four tips a week before the November midterm elections; that has increased to an average of five—and as many as 15—a week in the months since.

…“I’ve never seen this many whistle-blowers reporting waste, fraud, and abuse, and just general concern,” the senior Oversight Committee aide told me. “On the flip side of that, I’ve also never seen whistle-blowers so afraid of what could happen to them if somebody finds out who they are.”

…“I will protect whistle-blowers. Period,” the chairman declared.

Trump Whistle-Blowers Are Working With House Democrats – The Atlantic

hmmmm