Democratic presidential front-runner Hillary Clinton Hillary Diane Rodham ClintonHillicon Valley: FBI chief says Russia is trying to interfere in election to undermine Biden | Treasury Dept. sanctions Iranian government-backed hackers The Hill's Campaign Report: Arizona shifts towards Biden | Biden prepares for drive-in town hall | New Biden ad targets Latino voters FBI chief says Russia is trying to interfere in election to undermine Biden MORE said Wednesday she is not worried about the surge of her opponent, Sen. Bernie Sanders Bernie SandersMcConnell accuses Democrats of sowing division by 'downplaying progress' on election security The Hill's Campaign Report: Arizona shifts towards Biden | Biden prepares for drive-in town hall | New Biden ad targets Latino voters Why Democrats must confront extreme left wing incitement to violence MORE (I-Vt.), less than a month out from the Iowa vote.

“No I’m not nervous at all,” Clinton said on the “Today” show. "I’m working hard, and I intend to keep working as hard as I can until the last vote or caucusgoer expresses an opinion. I’m excited about where we are.”

Polls this week show Sanders gaining on or surpassing the former secretary of State in the first caucus state of Iowa and adding to his lead in the first primary state of New Hampshire.

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Clinton said she and Sanders have been introducing themselves to voters and “now it’s time to draw some contrasts.” In particular, she kept up her attacks on the Vermont senator’s record on gun control.

“One of the big [differences], as you’re aware, is on gun safety, where Senator Sanders has been a pretty reliable vote for the gun lobby, and I have been standing against them for a long time, voting against them as a senator.”

She also attacked Sanders for his vague healthcare proposals saying, “I've been laying out very specific policies for months now and telling people how I would pay for them.”

“I'm asking that Sen. Sanders does the same thing. We need to move now from generalization to specifics so people can see what the differences are.”

But, Clinton said, "the contrasts on substantive issues between me and Senator Sanders pale in comparison to between us and the Republicans.”

Clinton laughed when asked if GOP front-runner Donald Trump had found a weak spot by attacking former President Bill Clinton’s record with women, saying she wouldn’t engage on the issue.

"Donald Trump can run his campaign any way he wants."