Story highlights Clinton told the audience at the hilltop home that she was "feeling very good" about the state of her campaign

The former secretary of state noted her win in Nevada

Los Angeles (CNN) Hillary Clinton told an audience at a closed California fundraiser Monday that the top reason to defeat Republican front-runner Donald Trump in November is because of how his presidency would negatively impact the security of United States.

"There are a number of reasons to defeat Donald Trump, but chief among them is security," Clinton said after a long riff about how Trump's pitch to ban Muslims and other comments make it harder to work with Middle East nations and fight terrorism.

Clinton's blunt comment, while casting Trump as a risk to the nation's security, also leans into the chance that Trump could end up as the Republican standard bearer.

Trump handily won the South Carolina primary on Saturday, his second victory in his party's nominating process.

Clinton did not mention another Republican by name at the $2,700-a-head fundraiser but repeatedly hit the party writ large.

Read More