Donald Trump has attacked what he called media “hostility” in a speech to a campaign rally following a wave of pipe bombs sent to senior Democrats, prominent critics and the broadcaster CNN, during a midterms campaign rally in Mosinee, Wisconsin, on October 24.

The US president, who earlier said at the White House that he condemned the attempted bombings and that a “major federal investigation” was under way, followed this with a plea for unity at the Mosinee rally.

“Any acts or threats of political violence are an attack on our democracy itself,” he told the crowd. “We want all sides to come together in peace and harmony. We can do it … Those engaged in the political arena must stop treating political opponents as morally defective.”

But he soon reverted to a familiar scapegoat. The media, he said, has “a responsibility to set a civil tone and to stop the endless hostility and constant negative and oftentimes false attacks and stories”.

Authorities said on Wednesday that pipe bombs had been sent to prominent critics of Donald Trump, spreading terror in the US less than two weeks before the midterm elections.

Packages containing suspected explosives were sent to the homes of the former president Barack Obama and the former Democratic presidential nominee Hillary Clinton but intercepted by the US secret service. The packages are being analyzed by the FBI at its lab in Virginia.

Another suspect package, addressed to the former attorney general Eric Holder, was discovered before reaching its target. The FBI also reported finding two suspicious packages addressed to the Democratic congresswoman Maxine Waters. Federal investigators were additionally trying to track down a suspicious package they believe was addressed to Joe Biden, a US official told Reuters.

CNN evacuated its studios in New York after what police called a “live explosive device” was found in its mailroom. The package was addressed to John Brennan, the former CIA director, who has repeatedly clashed with Trump.

Some Democrats expressed fears that party figures were coming under attack ahead of the 6 November congressional elections. James O’Neill, the New York police commissioner, said the recipients may have been selected because of their opposition to Trump. “It is of concern to us,” O’Neill said.

Trump, who still assails Clinton at rallies while supporters chant “lock her up” two years after he defeated her, took a softer tone in Wisconsin. “Let’s get along,” he told supporters. “By the way, do you see how nice I’m behaving tonight? Have you ever seen this? We’re all behaving very well and hopefully we can keep it that way, right?”

He did not mention the intended recipients of the devices by name but spoke more generally, including in language which could be taken to refer to protests against himself and allies. “No one should carelessly compare political opponents to historical villains, which is done often, it’s done all the time, got to stop. We should not mob people in public places or destroy public property. There is one way to settle our disagreements. It’s called peacefully, at the ballot box.”

The packages were found after the discovery on Monday of a bomb in a mailbox at the New York home of George Soros, the billionaire liberal donor. The FBI said that device and at least four others found so far were in matching envelopes with similar address labelling and stamps.

Speaking at an event in Florida, Hillary Clinton said the US was in a “troubling time” and condemned divisive rhetoric by politicians. “We have to do everything we can to bring our country together,” said Clinton. “We also have to elect candidates who will try to do the same.”

Brennan suggested that he may have been targeted because of his past criticisms of Trump. “His rhetoric, I think, too frequently fuels these feelings and sentiments that now are bleeding over into, potentially, acts of violence,” the former CIA director said during an event in Austin, Texas.

He added: “One could make an argument that it has emboldened individuals to take matters into their own hands. So when he compliments individuals who have in fact body-slammed others, or that he’s going to pay the legal bill of somebody who takes a swing at somebody, that can only be seen as encouragement and incitement.”

Several influential supporters of the president tried, without evidence, to dismiss the attempted bombings as a liberal hoax.

But the idea caught on in some online chatrooms nonetheless and a sign reading “Democrats fake news fake bombs” was quickly spotted amid supporters of the Republican candidate for the Florida governorship, Ron DeSantis, ahead of a debate against his Democratic challenger, Andrew Gillum, on Wednesday evening.

Soros, Clinton and Obama are three of the most prominent figures in Democratic politics and have for years been the subjects of attacks and conspiracy theories from Donald Trump and allies in the Republican party and rightwing media.

Matt Gaetz, a Republican congressman from Florida, last week falsely suggested that Soros, a billionaire financier and philanthropist, was funding the “caravan” of Central Americans currently traveling through Mexico toward the US.

Alexander Soros, George Soros’s son, said a wave of vitriol against his father was unleashed by Trump’s 2016 presidential campaign. In an article for the New York Times, he said of the attempted bombing: “I cannot see it divorced from the new normal of political demonization that plagues us today.”

CNN is frequently singled out by Trump even as he leads a campaign to discredit the media generally. Trump tweeted an animated video in 2017 of him wrestling the CNN logo to the ground.

Jon Swaine and David Smith

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