Cryptocurrency prices briefly jumped after President Donald Trump’s surprise announcement he wants the U.S. government to purchase and hold a variety of digital assets in a strategic reserve fund, an announcement that highlights Trump’s growing attempts to use volatile cryptocurrency prices as a barometer of his public support.

Trump said on social media Sunday that his administration is working toward creating a “Crypto Strategic Reserve” that will include lesser-known cryptocurrencies XRP, solana, and cardano. He later followed up with another post saying his planned reserve would also include bitcoin and ether, the two most popular cryptocurrencies.