Expectations for a Fed bailout for markets and the economy rose sharply after President Donald Trump's surprise threat to put tariffs on all Mexican goods if Mexico doesn't do more to stop immigrants from entering the U.S.

Many investors believe in the "Trump put," — the idea that he would act to limit the stock market's downside because he views the market's performance as a reflection of his own success. But after Trump's announcement on Twitter on Thursday night, investors may be considering whether the Fed could be the real backstop.

That was evidenced in the sharp jump in market expectations Friday for a Fed rate cut. Fed funds futures were pricing a 64% chance of either a half percent rate cut or two quarter-point cuts by the end of the year.

J.P. Morgan Chase economists also promptly called for two Fed interest rate cuts by December, changing their view from an equal chance for either an interest rate hike or cut. Barclays economists also said they expect two rate cuts, one a half percent cut and a second quarter point cut, based on a slowing economy, extended trade war with China and the Mexican tariffs.

"If the Administration follows through on the proposed actions, we believe the adverse growth implications would prompt Fed easing. Even if a deal is quickly reached with Mexico, which seems plausible, the damage to business confidence could be lasting, with consequences that might still require a Fed response," the J.P. Morgan economists said in a note Friday morning. "Accordingly, we now look for two 25bp reductions in the federal funds rate target, in September and December."

The Fed has said it was pausing in its rate-hiking cycle, and it is on hold while it watches the economy. Increasingly, economists have moved away from the view that the Fed's next move will be a hike but traders have been betting on a cut for several months.

"The downside risk is greater than the upside," said Ed Keon, chief investment strategist at QMA. "It's hard to say whether these Mexican tariffs will go into effect or not. It just adds another brick to the wall of worry, which eventually we'll climb."

Keon said the idea of a Trump put still exists but it's surrounded by more uncertainty. "I think people still have the perception that he wants the market to go up, and he'll take action to help it, but that's not the only thing on his agenda and in some ways his whole campaign was based on eliminating illegal immigration. This is one of his core beliefs."

Trump added a new element of uncertainty to his use of tariffs, but it's not clear the tariffs will be implemented since two key advisors, U.S. Trade Representative Robert Lighthizer and Treasury Secretary Steven Mnuchin, reportedly disagree with the tariffs.

"So this is no more about free and fair trade, reciprocity, and protection of technological expertise. Tariffs can be thrown around as an economic bomb for anything now. Global growth rates will only continue to suffer," said Peter Boockvar, chief investment strategist at Bleakley Advisory Group.

The S&P 500 was 1% lower Friday, after Trump said he would start with 5% tariffs June 10 and raise them to 25% if Mexico does not stop the flow of immigrants across the U.S. border.