US President Donald Trump said he was directing the purchase of $200 billion in mortgage bonds, which he cast as his latest effort to bring down housing costs ahead of the November midterm election. 

Trump announced the move on Thursday in a social media post, which was unclear on how the buys would occur or which parties would make them.

READ MORE: GSE stock move stirs fears of advantage for big banks

"I am instructing my Representatives to BUY $200 BILLION DOLLARS IN MORTGAGE BONDS. This will drive Mortgage Rates DOWN, monthly payments DOWN, and make the cost of owning a home more affordable," Trump wrote in his post. 

He added that his decision not sell Fannie Mae and Freddie Mac during his first term allowed it to amass "$200 BILLION DOLLARS IN CASH" and that he was making his announcement "because of that."

"It is one of my many steps in restoring Affordability, something that the Biden Administration absolutely destroyed," the president said. 

READ MORE: How Fannie, Freddie product mix could shift with a stock offering

Trump on Wednesday said he would move to ban institutional investors from buying single-family homes. The president's advisers have repeatedly raised alarms that affordability has become a political albatross for the GOP and could cost the party control of Congress in the elections this fall. 

The Federal Housing Finance Agency, the regulator and conservator of Fannie Mae and Freddie Mac, did not immediately respond to a request for comment. 

READ MORE: What Fannie, Freddie uplisting would change for the GSEs