US President Donald Trump decried the threat of political violence and called on the media to end its "hostility" on Wednesday, hours after authorities intercepted bombs sent to a news network and prominent Democrats who have been the targets of some of his sharpest barbs.Trump's pleas for harmony came as law enforcement officials scrambled to find the perpetrator of the thwarted bomb attacks against former President Barack Obama, Hillary Clinton, CNN and others. The scripted message was a dissonant one for the president, who has repeatedly blasted his political opponents as criminals and argued that they will destroy the country if they win control of Congress in the midterms."We want all sides to come together in peace and harmony," he said at a campaign rally in Wisconsin. "Any acts or threats of political violence are an attack on our democracy itself."The president noted the unusually subdued tone of his remarks."By the way, do you see how nice I'm behaving tonight?" he said. "Have you ever seen this?"Reporters 'enemies of the people'Law enforcement authorities have ascribed no motive to the crime. Still, it has prompted immediate debate over whether increasingly personal and hard-edged rhetoric has contributed to a potentially dangerous political climate. Trump critics have blamed him for the tone.The president did not take any responsibility.Those "engaged in the political arena" must "stop treating political opponents as being morally defective", he said. He also referenced high-profile incidents in which conservatives have been accosted in restaurants and public spaces by political critics.He added: "The media also has a responsibly to set a civil tone and to stop the endless hostility and constant negative and oftentimes false attacks and stories."Trump has frequently labelled stories he doesn't like as "fake news" and many reporters as "enemies of the people".Trump spoke to thousands of supporters in a central Wisconsin rally as he looked to boost struggling Republican candidates less than two weeks out from the midterm elections. He visited the tiny city of Mosinee, which has a population of 4 000. He won that part of the state by double digits in 2016.Republicans in the state have been growing increasingly nervous about the prospects of holding onto the governor's office, held by Scott Walker, let alone state Sen. Leah Vukmir's chances of picking up a US Senate seat held by a well-positioned Democratic incumbent.Mindful of the national context, Trump refrained from delivering some of his regular routine critical of Democrats like Clinton and Rep. Maxine Waters, whose office appears to have been a target of one of the mail explosives.But he had harsh words for Democratic Sen. Tammy Baldwin, branding her Vukmir's "radical far-left opponent" ''who wants a socialist takeover of health care"."You know I'm trying to say that very nicely," he told the crowd with a smile. "Normally I'd scream, 'They want a socialist takeover!'" he said, mimicking his own bellicose delivery. "Now I say, 'Wants a socialist takeover'", he said, feigning a professorial tone."I'm trying to be nice."