Coalition senator Gerard Rennick has followed through on his threat to abandon the government on key parliamentary votes unless Scott Morrison winds back COVID regulations and vaccine mandates.

Senator Rennick said he is “not going to change my mind” even after pressure from senior ministers.

At the same time, the Queensland backbencher has suddenly become one of the most popular politicians on social media, regularly outstripping the Prime Minister and Anthony Albanese on engagement and interactions after relentlessly spreading what Labor has slammed as “anti-vax propaganda”.

“We’re talking out of both sides of our mouth,” Senator Rennick said of the federal government.

“We’re saying we don’t believe in vaccine mandates, but we’re giving vaccines to the [Premiers] who are making the mandates … it’s going to cause some heartache.”

Senator Rennick sent a letter to Scott Morrison. Photo: AAP

Senator Rennick told the Coalition party room in mid-October that he’d “withhold” his vote from the government unless Mr Morrison “pushed back” on state premiers keeping borders closed due to COVID-19.

At the time, he told The New Daily he had had a “gutful” of coronavirus regulations.

On Sunday, the Senator posted on Facebook a copy of a letter he said he’d sent to Mr Morrison, advising of his “intention to withhold my vote from the Coalition” unless the government took action on a list of five grievances.

He called for an end to workplace-mandated vaccinations, and the “repeal” of state border closures.

Most of his grievances were issues for state governments, not federal, but Senator Rennick said the federal Coalition should be pressuring state premiers to change their tune.

“We’ve let the premiers overreach on things for too long. We say it’s their decision, but we fund them,” he told TND.

Senator Rennick said several senior ministers had contacted him about his concerns, but he wouldn’t vote in favour of government legislation in the Senate “until it changes”.

He said he wouldn’t vote for non-government motions, only that he’d withhold his vote from the Coalition.

Rennick’s profile grows after allegations of  ‘anti-vax’ Facebook posts

Elected third on the Liberal National Party’s Senate ticket at the 2019 election, and currently holding no ministerial or committee chair positions, Senator Rennick is not among the Parliament’s most well-known members.

But the rift with his government coincides with a surge in his social media numbers to all-time highs.

Despite having just 36,000 Facebook followers, Senator Rennick’s social media engagement and interaction numbers are consistently outranking those of Mr Morrison, Mr Albanese, One Nation’s Pauline Hanson, Greens leader Adam Bandt and Treasurer Josh Frydenberg.

Senator Rennick’s letter to the PM was the most popular Facebook post of any federal politician on Monday.

The Senator has been posting multiple stories of alleged adverse effects of COVID vaccines to his Facebook page.

In its weekly reports on the very small number of adverse events, Australia’s Therapeutic Goods Administration stresses “the protective benefits of vaccination continue to far outweigh the potential risks”.

Facebook automatically places a warning label on many of Senator Rennick’s posts, advising that vaccines “go through many tests for safety and effectiveness and are then monitored closely”, and linking users to official sources of health information.

Nonetheless, the Senator’s Facebook fans have nearly doubled in the past week alone, from 20,000 on October 23 to roughly 36,000 on Monday, according to social media monitoring tool CrowdTangle.

He regularly gets many thousands of likes, comments and shares on his content.

Senator Rennick’s post about his letter to Mr Morrison had more total interactions than any post by any federal politician in the 24 hours to 5pm on Monday.

Recent posts opposing vaccine mandates have been among the most popular posts among Australia’s federal politicians, while more than 11 per cent of all interactions on Australian politicians’ pages on Friday were on posts from Senator Rennick.

His posts have been praised by former One Nation Queensland leader Steve Dickson and United Australia Party MP Craig Kelly.

The TGA releases weekly reports on vaccine adverse effects.

In its latest report, the TGA had received 2.2 reports of adverse effects per 1000 doses, with complaints ranging from frequently-reported symptoms like headaches and arm soreness, to very rare occurrences of more serious issues.

“Vaccination against COVID-19 is the most effective way to reduce deaths and severe illness from infection,” the TGA said.

Of the most serious side effects, the TGA was aware of 235 cases of likely myocarditis from 21 million doses of Pfizer – a rate of 1 in 90,000.

Of the 12.9 million doses of AstraZeneca’s vaccine, the TGA was aware of just 157 likely cases of thrombosis with thrombocytopenia syndrome (or TTS) – or 1 in 82,000.

Senator Rennick claimed he was not an “anti-vaxxer”, and had received vaccines like that for whooping cough, but said he hadn’t taken a COVID vaccine.

Last week, during a Sky News TV panel segment, Labor’s Murray Watt accused the Coalition senator of “anti-vax propaganda” and claimed his actions “undermine [the] vaccine rollout”.

“What you’re posting is nonsense,” Senator Watt told Senator Rennick on the program.

“You’re an anti-vaxxer.”

Senator Rennick denied this, saying “I’ve got my children vaccinated. I got my whooping cough.”

Senator Rennick said he planned to keep posting this content online, but was surprised by the social media statistics when informed by TND of his sudden engagement spike.

“I’m not aware of it and frankly I don’t care,” he said.

“I can’t keep up with the comments.”