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President Trump wrote over Twitter on Saturday that 'if anyone but me takes over in 2020 ... there will be a Market Crash the likes of which has not been seen before!'

As President Donald Trump prepares to launch his 2020 campaign, he posted a warning over Twitter: If he's not elected, the markets will crash.

"The Trump Economy is setting records, and has a long way up to go," wrote Trump over Twitter. "However, if anyone but me takes over in 2020 (I know the competition very well), there will be a Market Crash the likes of which has not been seen before!"

Earlier, the president announced on Twitter that his campaign will launch on Tuesday in Florida.

"Tuesday will be a Big Crowd and Big Day!" he said.