Trump has solid backing for his war from establishment Republicans.

But while those same Republicans had long dreamed of regime change in Tehran, both Trump's rise to power in 2016 and his return to the White House last year were fueled by isolationist "America First" ideology and rejection of all post-9/11 wars.

"GOING INTO THE MIDDLE EAST IS THE WORST DECISION EVER MADE," Trump blasted on social media in his trademark all-caps back during his first term in 2019.

Or, as he said during his 2024 campaign to recapture the White House: "I don't want to see wars."

That message helped Trump build his Make America Great Again movement, supposedly putting the era of unpopular conflicts in Iraq, Afghanistan and elsewhere into the rearview mirror.

So the massive US-Israeli attack on Iran and Trump's call for ousting the country's Islamist leadership has Planet MAGA in a spin -- and that's a risk ahead of November elections for Congress.

"If the administration moves towards... more military tactics, a more aggressive posture into Iran, I think that that could be detrimental for Republicans going into the midterm elections," former Trump advisor Mercedes Schlapp told CSPAN television.

- 'Lie' -

One of the first to lash out has been hard-right firebrand Marjorie Taylor Greene.

She resigned her seat in Congress early this year amid a bitter falling out with Trump but remains an influential figure in MAGA circles.

Greene called the Iran attack "a lie."

Trump, she said, had been elected on promises of no more foreign wars and "to put America FIRST," she posted on X.

"It's always a lie and it's always America Last. But it feels like the worst betrayal this time because it comes from the very man and the admin who we all believed was different and said no more."

Influential right-wing broadcaster Tucker Carlson described the attack on Iran announced by Trump early Saturday as "absolutely disgusting and evil."

"This is going to shuffle the deck in a profound way," he told ABC News correspondent Jonathan Karl.

Nick Fuentes, another influencer with extreme views, has been railing against the war talk for weeks, predicting Republican electoral wipeouts.

"Every day I am more vindicated," he posted on X as the raid on Iran began.

- Clean victory? -

Trump however could yet come out on top.

The one-day operation in January to oust Venezuela's longtime strongman leader Nicolas Maduro, without losing a single American service member, demonstrated the US military's reach.

Trump also ordered a spectacular one-off bombing raid on Iran last year that he claimed had destroyed the country's disputed nuclear program. Again, there were no US losses and Trump revels in the display of raw power.

But the current Iran operation is vastly more complex and could drag on for weeks. Critics are already asking what the goals are, particularly given the supposed destruction of Tehran's nuclear facilities months ago.

Trump himself acknowledged "we may have casualties."

If things get messy, Trump will have some explaining to do to his MAGA faithful.

After all, it was his top aide Stephen Miller who best summed up the Trumpian message on the eve of the 2024 election against Kamala Harris.

"Kamala = WWIII. Trump = Peace," Miller posted.