Vermont Sen. Bernie Sanders called Sunday for a "political revolution" that would take on the "billionaire class" and usher in a European-style system that would be fairer to ordinary working Americans.

"We need a political revolution in this country involving millions of people who are prepared to stand up and say, enough is enough, and I want to help lead that effort," the self-proclaimed socialist told ABC's "This Week" when asked why he was seeking the presidency.

Host George Stephanopoulos questioned whether the country was ready to elect an avowed socialist.

"Well, so long as we know what democratic socialism is," Sanders responded. "And if we know that in countries, in Scandinavia, like Denmark, Norway, Sweden, they are very democratic countries, obviously. The voter turnout is a lot higher than it is in the United States. In those countries, health care is the right of all people. And in those countries, college education, graduate school is free. In those countries, retirement benefits, child care are stronger than in the United States of America. And in those countries, by and large, government works for ordinary people and the middle class, rather than, as is the case right now in our country, for the billionaire class."

Asked about how he would differentiate himself from Hillary Clinton, Sanders steered clear of attacking the Democratic front-runner in favor of touting his own record as a fighter for ordinary Americans.

"I think it has a lot to do with our records," Sanders said. "I think at a time when we have seen trillions of dollars shift from the middle class to the top one-tenth of 1 percent, we have got to say very frankly that the wealthiest people in this country and the largest corporations are going to have to start paying their fair share of taxes; profitable corporations can't stash their money in the Cayman Islands and avoid about $100 billion a year in taxes."

While Sanders may be an overwhelming underdog to defeat a much better funded Clinton in the Democratic primary, he noted that he had raised $1.5 million in the 24-hour period after announcing his candidacy, and that the average donation was just $43. Running to the left of Clinton on issues like trade, climate change and financial-sector regulations, Sanders sees his campaign not so much as against the former secretary of state. Instead, his candidacy is meant to pull the country away from being a "battle between billionaires."

Whether he can convince enough voters that he represents a viable alternative to Clinton, Sanders sounded optimistic.

"I would say don't underestimate me," Sanders said.