Perched on the side of the bridge connecting the island of Palm Beach to the Florida mainland, a day after Donald Trump’s nearby Mar-a-Lago resort was searched by the FBI, Mary Ann Robinson held a White Claw alcoholic drink in one hand and railed against federal law enforcement.

“When they raided our president[’s home], I felt hurt, then anger,” said the retired healthcare administrator. “I come to these rallies to bring attention to what is happening in our government. We know the Godless commies will never take this republic down as long as we are here.”

Robinson was part of a relatively small group of defiant, diehard pro-Trump supporters, who were staging what was largely a drive-by defence of the former president on Tuesday, many of them brandishing huge flags and blaring their car horns.

Their reactions were laced with conspiracy theories about both the 2020 election and the political motivation behind the FBI search, echoing Trump’s own statement on the raid. They also ominously suggested that the backlash could turn violent — particularly if the former president was arrested or prevented from seeking re-election in 2024.

“We’re going to fight until the end, whatever it takes,” said Mark Harvey, a Florida local who fishes in the waters around the Trump residence and introduced himself as “Beach Cracker”. “Ninety-nine per cent of Republicans are armed and ready to go. We’re ready to take it to the next level if it comes down to it.”

Such threats and fury weren’t just confined to Palm Beach. From the moment Trump announced that his home had been searched by federal agents, anger rippled across conservative America.

Republican lawmakers lashed out at the FBI and the justice department for being complicit in an oppressive federal regime and a “deep state” bureaucracy that was out to quash any political opposition — even though the search on Mar-a-Lago was approved by a federal judge.

“DEFUND THE FBI!” Marjorie Taylor Greene, the Republican lawmaker from Georgia and one of Trump’s closest allies on Capitol Hill, wrote on Twitter.

Other Republicans tied the FBI’s move on Trump to the $700bn economic package recently passed by the Senate and endorsed by president Joe Biden. The bill includes a measure beefing up funding for the Internal Revenue Service to audit more wealthy tax evaders — something some conservatives characterised as another sign of impending government persecution.

“The federal Regime is targeting those it dislikes for disfavored treatment,” Florida governor Ron DeSantis told his supporters in a fundraising email on Wednesday. “They are demanding we get in line or face the consequences. Now, the Regime is getting another 87,000 IRS agents to wield against its adversaries.”

When Scott Perry, a Republican lawmaker from Pennsylvania who is one of Trump’s most loyal followers on Capitol Hill, disclosed that his phone had been seized by the FBI on Tuesday after facing scrutiny from a congressional probe over the January 6 attack on the US Capitol, more anger flared on the hard right.

“This is America, and these Gestapo tactics are not welcome. There will be a reckoning,” Lauren Boebert, the pro-Trump Republican lawmaker from Colorado, said on Twitter.

The response has highlighted the extent to which many Republicans have drifted towards Trumpian scepticism of federal law enforcement in a party that has traditionally presented itself as tough on crime.

Even senior Republican leaders in Congress openly attacked the DoJ and the FBI in the wake of the search, with Kevin McCarthy, the top Republican in the House, vowing to probe attorney-general Merrick Garland if they regain control of the lower chamber of Congress in November.

Meanwhile, Republican candidates for office launched fundraising pledges on the back of the search and promised retribution. “The question is what comes next,” said JD Vance, the author and venture capitalist running for a Senate seat in Ohio. “We either have [a] Republic or we don’t. If we do, the people who’ve politicised the FBI in recent years will face investigation and prosecution.”

Republican strategists hope that the raid will consolidate their advantage with US voters heading into the midterm elections by revving up their base. But there is a risk that the anger unleashed may turn off moderate and independent voters by showing how deeply anti-Washington extremism has penetrated the GOP and the extent to which the party remains in Trump’s grip.

On social media, the rage flared up just as strongly. In the hours following the news of the Mar-a-Lago raid, tweets referencing “civil war” and “FBI Gestapo” surged to a peak of over 3,000 in one hour. Two days later, an average of 1,000 of these tweets were still being sent every hour.

Many on Twitter, Telegram and Trump’s alternative platform TruthSocial pointed to the raid as evidence of continued targeting of Trump and his supporters by Biden and the so-called deep state. Baseless online conspiracies spread rapidly on Tuesday and Wednesday accusing the FBI of planting evidence to prevent Trump from running for office in 2024.

In far-right spaces such as QAnon Telegram channels and the message boards TheDonald and 4chan, threats of violence were more explicit and targeted, with many posting death threats against Garland and FBI director Christopher Wray. One popular post on TheDonald read: “They have awakened a Dragon and it’s coming for them.”

Meanwhile, former Trump campaign manager Steve Bannon, who was convicted of contempt of Congress for refusing to comply with a subpoena in the January 6 probe into the 2021 attacks on the Capitol in Washington, urged supporters to mobilise. “Right now, we unite, we run the fricking tables in November. I’m talking about 100 seats,” he said on The Alex Jones Show on InfoWars on Tuesday.

“Get an overwhelming majority in the House, take the Senate, take every school board, every election board, every canvassing board, every medical board in every state,” he added.

But it was outside Trump’s adoptive Florida home that feelings were at their most raw — and disturbing. “When the FBI raided Trump’s home, we stepped into an entirely new realm,” said Charles Molesphini, a retiree from Delray Beach, Florida, who smoked a cigar while his car blared out the national anthem from under a draped American flag.

Linda Ulmer, a retiree from Jupiter Beach, Florida, who owned a commercial construction company with her late husband, added: “If Trump is put in prison, there will be a civil war. People will be out on the streets. Buildings will burn. People will take down the Capitol.”