Republican presidential candidate Donald Trump’s rivals his hard-line immigration plan savaged when it was in a televised debate.
The billionaire was booed shortly after urging illegal migrants to be deported.
Two of his rivals for the Republican nomination, John Kasich and Jeb Bush, were very critical, saying his plan was impractical and divisive.
The top eight presidential contenders in the party are squaring off in Milwaukee for the fourth time.
Mr Trump reiterated his calls for a wall to be built at the US-Mexico border and for migrants currently living illegally in the US to be deported.
Mr Kasich, the governor of Ohio, shot back imploring his opponent to “think about the children”.
“It’s a silly argument,” he said of Mr Trump’s plan. “It’s not an adult argument.”
Mr Bush, the former Florida governor under pressure to revive a flagging campaign, also condemned the plan, saying it would tear families apart.
But New York businessman Mr Trump strongly supported his plan and told that illegal immigration hurt the US economy.