A range of high-profile conservatives have embraced a conspiracy theory that mail bombs sent to liberal public figures are a “false flag” attack by leftwingers. Many have also claimed that the attacks are intended to elicit sympathy for Democrats ahead of the looming midterm elections.

Authorities are yet to identify a suspect or motive in the bombings, which have seen 12 pipe bombs sent to a range of figures from former president Barack Obama to Bill and Hillary Clinton to financier George Soros and even to the out-spoken actor Robert De Niro. All the suspects have one thing in common: they have been targets of Donald Trump’s ire.

Nevertheless, without evidence, a number of ostensibly mainstream conservatives joined more overtly conspiracist outlets in either expressing skepticism that conservatives would damage their own cause, or making outright accusations that the left are orchestrating the bombing campaign in order to sabotage Republicans.

In a now-deleted tweet, on Thursday Fox Business TV host Lou Dobbs wrote: “Fake News – Fake Bombs. Who could possibly benefit by so much fakery?” Dobbs has a close relationship with Trump and the two reportedly speak frequently on the phone.

Elsewhere on Fox, three guest analysts suggested that the bombs were “false flag” attacks.

Also on Thursday, the president’s son, Donald Trump Jr, liked a tweet which read in part: “FAKE BOMBS MADE TO SCARE AND PICK UP BLUE SYMPATHY VOTE.” In the past he has liked tweets questioning whether the Parkland survivor David Hogg was actually present at the Florida school shooting that led him to become gun control campaigner.

On Wednesday, after a caller said the bomb plot didn’t “pass the smell test”, the leading talk radio host Rush Limbaugh asked rhetorically: “Would it make a lot of sense for a Democrat operative or Democrat-inculcated lunatic to do it? Because things are not working out the way they thought.”

His fellow rightwing broadcaster, Michael Savage, opined the same day that there was a “high probability that the whole thing had been set up as a false flag to gain sympathy for the Democrats”, and to distract from the so-called “caravan” of migrants currently in southern Mexico.

The far-right and anti-immigrant media personality Ann Coulter, meanwhile, claimed on Wednesday that the “bombs are a liberal tactic”. The conservative author and film-maker Dinesh D’Souza, whose recent work has drawn parallels between Democrats and Nazis, tweeted: “I hear the FBI squeezed lemon juice on the suspicious packages and a very faint lettering revealed a single word: DEMOCRATS.”

Those further down the conservative media pecking order were also on message with “false flag” allegations.

The Trump-aligned podcaster and social media star Bill Mitchell described the bombs as “Soros astro-turfing”, referring to the billionaire philanthropist (and magnet for conspiracy theorists) who was the first target of the bombing campaign. He added that the attacks were “Pure BS”.

Rightwing cartoonist Ben Garrison drew a cartoon entitled Raising a false flag, featuring Hillary Clinton, CNN media reporter Brian Stelter, and former CIA director John Brennan – all bombing targets – raising a flag shaped like a mail bomb. Underneath the flag, he has George Soros exclaiming: “See? We’re victims of Trump’s hate!”

In the past, “false flag” theories have mostly been aired in more openly conspiratorial media outlets like Alex Jones’s Infowars.

The term has been used by Jones and other conspiracy theorists to allege that violent attacks have been carried out not by their apparent authors, but by powerful, manipulative actors seeking to deceive observers and hide their own responsibility. Its adoption this week by a broad range of rightwingers suggests an increasing openness to conspiracy theory in more mainstream conservative media.

Jones was himself banned from most social media platforms earlier this year over his longstanding claims that the Sandy Hook school shooting was faked, and employed “crisis actors” in order to build support for gun control in the United States.

Jones was also a part of the so-called 9/11 Truth Movement, members of which asserted that the 2001 attack on the World Trade center in New York had been a “false flag” on a grand scale. Many truthers alleged that the attack was orchestrated by the Bush administration in order to provide a justification for the invasion of Iraq.

On Wednesday, just hours after multiple bombs had arrived at the homes of former public officials and the offices of media companies, Jones alleged that the bombs had been planted by leftist antifascist or “antifa groups”, in order to “smear conservatives who support President Trump”.