Former President Obama is “livid” with anger about President Trump’s latest accusations of wiretapping and hasn’t returned the new commander in chief’s phone calls since the inauguration, according to a new report in The Wall Street Journal. Trump reportedly called his predecessor to thank him for the letter he left in the Oval Office but that overture was never returned. Trump tweeted on Saturday: “How low has President Obama gone to tapp my phones during the very sacred election process. This is Nixon/Watergate. Bad (or sick) guy!” He has since provided no evidence for his claims. Sources close to Obama told the Journal that the former president was angry over the accusation. Presidential historian Douglas Brinkley said the apparently fraught relationship is a break with tradition. “There are these kinds of things that have happened in the past, but nothing to the degree where a sitting president would charge his predecessor with a felony,” Brinkley said. “It creates a feeling of instability in the United States.”