Hillary Clinton said Sunday that Donald Trump's personal attacks against her and her husband are "his prerogative" but will ultimately be "a dead end" for the Republican Party.
"It's been fair game going back to the Republicans for some years," Clinton said on CBS' "Face the Nation." "I think it's a dead end, blind alley for them, but let them go."
"He can say whatever he wants to about me," the Democratic front-runner said of Trump's attacks.
Clinton, who just last week said that her New Year's resolution was to ignore Trump, dismissed his most recent spate of attacks and said voters will be the ultimate judge of her character and policies.
In response to an email from 2011 that is raising new questions about whether Clinton mishandled classified information, the former secretary of state insisted she never sent any classified information on her private server.
"That did not happen and it never would have happened because that's just not the way I treated classified information," Clinton said. "There is nothing to that."
Clinton called the controversy another instance of "people looking for something to throw against the wall… but there's no there there."
In recent days, the Clinton campaign has made a concerted effort to point out differences between Clinton and her chief rival, Vermont Sen. Bernie Sanders, on gun control.
On Sunday, Clinton slammed Sanders for his 2005 vote that gave gun manufacturers immunity in court.
"I think that the excuses and efforts by Sen. Sanders to avoid responsibility for this vote, which the NRA hailed as the most important in 20 years, points up a clear difference," she said.
A new NBC/WSJ/Marist poll shows Clinton and Sanders are neck-and-neck in Iowa and New Hampshire.
Asked about the tightening race, Clinton said, "These polls go up, they go down. I stay pretty focused."
This article first appeared on NBCNews.com.