Obama told ABC News he wants to serve a second term "badly" because he thinks "the country needs it."
"Whoever wins the Republican primary is going to be a standard-bearer for a vision of the country that I don't think reflects who we are," Obama said Thursday. "I'm going to fight as hard as I can with every fiber of my being to make sure that we continue on a path that I think will restore the American dream."
He called his proposal to tax millionaires a "fair, sound approach" to reducing the deficit while rebuilding the country.
"[We] now have the lowest tax rates in 50 years. We've seen the highest increase in income for the very top echelons since the 1920s. And if, in fact, we're going to reduce our deficit while still investing in those things that we know make America grow, somebody's got to pay for it," Obama said.
"I think better I pay for it or Mr. [Mitt] Romney pay for it or Mr. [Newt] Gingrich help pay for it than a senior citizen suddenly seeing several thousands of dollars in additional Medicare increases or a student who's trying to struggle their way through school," he told ABC News.
Obama also took Gingrich to task for characterizing him as the "food stamp president."
"First of all, I don't put people on food stamps," he said. "People become eligible for food stamps. Second of all, the initial expansion of food stamp eligibility happened under my Republican predecessor, not under me. No. 3, when you have a disastrous economic crash that results in 8 million people losing their jobs, more people are going to need more support from government."
He said it will be up to voters to decide "who's trying to bring the country together and who's dividing it, who reflects the core values that helped create this country ... and who is tapping into some of our worst instincts."