President Donald Trump accused President Barack over the weekend of wiretapping him during the 2016 presidential election, comparing it to the anti-communist probes in the 1950s known as McCarthy hearings.  "Terrible! Just found out that Obama had my 'wires tapped' in Trump Tower just before the victory," Trump tweeted Saturday. "Nothing found. This is McCarthyism!" 

Trump offered no evidence to support his claims, which might remind many Americans of the McCarthy hearings, an era known as the Red Scare that targeted liberals in American by labeling them communists despite little evidence to back such accusations. Trump's lifelong attorney, Ray Cohn, was also close to former U.S. Sen. Joseph McCarthy, the lawmaker who started the probes. 

So what exactly is McCarthyism? After the Soviet Union and United States worked together to defeat Nazi Germany in World War II, Washington became concerned about the global spread of communism. McCarthy, a Republican from Wisconsin, stroked such tensions by alleging that communist spies had infiltrated the U.S. government. His claims saw people blackballed simply for being accused of having communist affiliations, despite a special Senate subcommittee concluding after an investigation that  McCarthy's charges were “a fraud and a hoax,”

Decades later, Repulicans are comparing calls for an investigation into the Trump administration's ties to Russia to McCarthy's hearings. House Intelligence Committee Chairman Devin Nunes, a Republican lawmaker from California, has said calls for a special prosecutor to investigation Trump and his advisers are based on speculation, not facts. "This is almost like McCarthyism revisited," Nunes told reporters in February. “We’re going to go on a witch hunt against innocent Americans?"

Trump's critics have also cited McCarthy to blast the White House. "Sen. McCarthy excelled at building on the public's FUD - Fears, Uncertainties and Doubts. At the time, Americans were terribly afraid of communists. Fearful they would ruin the U.S. social order and make the country into the next Soviet Union. So Sen. McCarthy conveniently blamed all social ills on communist infiltrators - people working in government jobs who were set on destroying the country. He then would accuse those he didn't like of being communists," a Forbes op-ed read in 2016. "Few have ever demonstrated the skills of McCarthyism better than Mr. Trump."