Republican Donald Trump's plan to deport 11 million undocumented immigrants from the US has been savaged by his party rivals in a TV debate.
His hardline proposal was attacked as impractical and divisive by John Kasich and Jeb Bush, who are also running for the Republican presidential nomination.
Mr Trump, a billionaire New Yorker who has been leading in the polls, was booed as he tried to counter-attack.
Another source of friction at the debate in Milwaukee was foreign policy.
The eight candidates were divided on whether the US should do more to intervene in the Middle East, especially in the fight against Islamic State militants.
But immigration sparked the biggest confrontation, when Mr Trump said a wall should be built at the US-Mexico border and all migrants living illegally in the US must be deported.
This was met with disdain by Mr Kasich, the governor of Ohio.
"Come on, folks, we all know you can't pick them up and ship them back across the border. It's a silly argument. It's not an adult argument."
Mr Bush, the former Florida governor, said it would tear families apart and played into the hands of Democratic frontrunner Hillary Clinton.
Other highlights:
- Mr Trump said the US should look at what Israel had achieved when it came to building a border wall
- He also slammed the Trans-Pacific Partnership and China's "currency manipulation" but seemingly did not realise that China was not party to the trade deal
- Marco Rubio called Rand Paul "a committed isolationist" and made the case for a "strong" US foreign policy
- Mr Bush was scathing of Mr Trump's anti-interventionist views and said the US "better be the world's leader"
- Senator Ted Cruz counted the Department of Commerce twice when naming five government agencies he would shut - in a gaffe reminiscent of Rick Perry's 2011 debate meltdown
The debate, hosted by Fox Business, began by talking about raising the minimum wage, which several candidates opposed.
