This was uttered by President Trump in a December 5, 2019 tweet. Here it is:
..trial in the Senate, and so that our Country can get back to business. We will have Schiff, the Bidens, Pelosi and many more testify, and will reveal, for the first time, how corrupt our system really is. I was elected to “Clean the Swamp,” and that’s what I am doing!
Trump’s mantra has always been “drain the swamp”, so I believe this is a malaphor, conflating “drain the swamp” with “clean house”, both meaning to wipe out corruption or inefficiency. A big thanks to Sandor Kovacs for spotting this one and sending it in.