Cryptocurrency prices 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.

A weekend boost for five crypto tokens, courtesy of a social media post from the president, fizzled out by mid-Monday morning.

Crypto markets were mostly back in the red on Monday, with XRP, SOL, and ADA each suffering intraday declines of more than 10 percent after soaring the day before.