The Federal Reserve next month will be forced to hike interest rates for a fourth time in 2018 or risk being seen as politically coerced, economist Mohamed El-Erian told CNBC on Tuesday. "It is very hard for the Fed right now to go back to three hikes," the chief economic advisor at Allianz said on "Squawk Box." "If they don't [hike], the market is going to say the economy is much weaker than we anticipated and/or the Fed is much more open to political intervention." President Donald Trump has repeatedly expressed frustration with the Fed's moves to raise rates, arguing the central bank could disrupt the U.S. ... (full story)