U.S. Sen. Bernie Sanders, the self-described "democratic socialist" from Vermont, has jumped into the 2016 presidential race.
Although a political independent, he's running as a Democrat and is currently the only alternative to Democratic frontrunner Hillary Clinton.
He's running on a progressive message, emphasizing what he describes as "massive and grotesque levels of income and wealth inequality."
"The top 1/10th of 1 percent owns as much as the wealthiest bottom 90 percent. That type of economics is not only immoral, it's not only wrong - it's unsustainable," Sanders said.
On Thursday, Sanders said that questions about the Clinton Foundation's activities are fair game in the race for the Democratic nomination, and noted that Clinton has yet to take a position on contentious trade legislation and the proposed Keystone XL Pipeline.
At a news conference with the U.S. Capitol as a backdrop, Sanders said creating "an economy that works for all of our people" would be at the center of his campaign for the Democratic nomination. "The wealthiest people in the country and the largest corporations" must stop shipping jobs overseas and start paying their fair share of taxes, he said.
He spoke not long after filing papers for his launch and as his team came out with a new website. It says, "A political revolution is coming," and has a disclaimer that it is "paid for by Bernie 2016, not the billionaires."
Sanders said he remains a political independent, but drew a tweeted welcome to the race from Florida Rep. Debbie Wasserman Schultz, head of the Democratic National Committee. "Sanders has clearly demonstrated his commitment to the values we all share as members of the Democratic Party," she posted.
And Clinton tweeted: "I agree with Bernie. Focus must be on helping America's middle class. GOP would hold them back. I welcome him to the race."
He is the first major challenger to enter the race against Clinton, who launched her own bid for president earlier this month and is the heavily favored, early front-runner in the Democratic contest. Former Maryland Gov. Martin O'Malley and former Virginia Sen. Jim Webb are potential contenders, and ex-Rhode Island Gov. Lincoln Chafee recently said he intends to run.
When asked how he will be different from Clinton, Sanders, 73, also points to his 2002 vote against the Iraq war, then how Clinton voted for it.
"I think Bernie understands he's not going to be the next president. He's in this to make a statement. He's in this to push Hillary Clinton a little further to the left," Democratic political analyst George Bachrach said.
Bachrach says Sanders is a positive in the race, but that he faces an uphill battle - raising money.
"To be a credible candidate, he actually has to open up offices, hire staff, otherwise he is just a guy with a suitcase hopping planes," he said.
It is a point Sanders does not dispute.
"Certainly we're going to be heavily outspent. I think it's fair to say the Koch Brothers and other billionaires will not be contributing to my campaign. I will be getting small campaign contributions," Sanders said.
Other key issues for Sanders will be climate change, tuition free colleges and universities and heavier regulations for Wall Street.
Sanders warns he should not be underestimated.
The Associated Press contributed to this report.