One of Hillary Clinton‘s closing arguments in the countdown to the Iowa caucuses is that she’s the best bet to win a general election against Donald Trump, Sen. Ted Cruz or other GOP hopefuls pushing ideas that are anathema to Democratic voters.

A new ad released by Mrs. Clinton’s campaign seeks to remind Democrats of the stakes in the 2016 race. It features a montage of belligerent-sounding Republican candidates and casts Mrs. Clinton as best positioned to keep them out of the White House.

“Who’s the one candidate who can stop them? Hillary Clinton,” the narrator says.

How about Bernie Sanders, Mrs. Clinton’s chief rival for the Democratic nomination? Could he stop them?