Democratic presidential candidate Hillary Clinton has rebuked Republican campaign rival Donald Trump saying "I no longer think he is funny".
Ms Clinton had downplayed the former TV star, making jokes about his campaign.
She said her rival's recently proposed ban on Muslims entering the US was "dangerous".
Mr Trump set off global condemnation with his ban idea, which came days after a Muslim couple attacked a health centre in San Bernardino, California.
A recent poll showed that a majority of Americans opposed Mr Trump's ban idea, while 25% of those polled were in favour of it.
"Now he has gone way over the line," Ms Clinton said during an appearance on Late Night with Seth Meyers. "What he is saying now is not only shameful and wrong, it is dangerous".
She said that Mr Trump is giving groups like the so-called Islamic State (IS) "a great propaganda tool" and "a way to recruit more folks from Europe and the United States".
Mr Trump's proposal earlier this week was met with an intense backlash in the US and across the globe from leaders who said it was divisive.
