Hillary Clinton: I "always expected" a tight Democratic race

Just two weeks away from the first Iowa caucuses, Democratic presidential candidate Hillary Clinton is losing ground to rival Bernie Sanders in the polls -- but, as Clinton tells CBS News, she's not surprised by the close numbers.

"I always expected that this would be a tight race," she said in a "CBS This Morning" interview early Wednesday. "That's the experience that I've had certainly in politics and I'm very happy about where my campaign is."

She added that "it's going to be a campaign that goes right to the wire."

Clinton also refuted a comment from Sanders that her campaign is "getting nervous."

"I just have a different sense of the rhythm of a campaign," she said. "Now, we're in the sprint to the finish line."

"The difference between Senator Sanders and myself pale in comparison to the differences between us and the Republicans," Clinton continued. But, she said"there are differences."

Clinton hammered Sanders particularly on gun control, saying that the two had a "different approach to how to end gun violence and try to protect our kids." The former secretary of state also pointed to their separate policies on health care and taxes for the middle class.

Clinton also disputed a recent statement from Vice President Joe Biden, who said Clinton was "relatively new" to the income inequality fight.

"I have the greatest respect for him," Clinton said, but pointed to her record as a lawyer for the Children's Defense Fund and her public service career as proof that she has been "fighting to even the odds for people" her entire life.

Despite the latest Democratic poll numbers -- which show Clinton ahead of the Vermont senator by just seven points nationally -- Clinton promises to keep her sights on the general election and her Republican rivals.

"This is the 'let's get real' part of the campaign where we talk about what we will do and compare and contrast and obviously take on the Republicans -- because that's where the real threat to our country's future lays," she said.

Clinton also commented on President Obama's final State of the Union address, defending the chief executive's claims that the U.S. remains an economic powerhouse.

"We fell into a great recession, the worst financial crisis since the Great Depression, and it's been a challenge to dig us out of a ditch that the president had nothing to do with digging," she said.

"The president's views are ones that are rooted in a lot of reality," she said. Still, Clinton added, "I'm out on the campaign trail saying that we've got to go further. We all know about making sure health care works, education works and all the rest. But we have to be looking over the horizon about how we remain a prosperous, strong country dealing with climate change and so much else."