Watch CNN's Wolf Blitzer interview Sen. Bernie Sanders on "Wolf" on Thursday at 1 p.m. EDT.
Washington (CNN)Bernie Sanders is in.
The independent Vermont senator railed against the political machine — blasting "ugly 30-second ads," billionaire big-money donors and other "soap opera aspects of modern campaigns" — in a press conference kicking off his candidacy outside the Capitol on Thursday.
"I think the American people are tired of that," Sanders said.
He said he is running to thwart trade deals like the 12-country Trans-Pacific Partnership and to overhaul business tax rules so corporations operating in the United States cannot shelter their money overseas.
"Their responsibilities are not to shift jobs to China, their responsibility is not to avoid paying federal taxes," he said.
Sanders first announced his run in an email to supporters and media sent just after midnight early Thursday morning.
"After a year of travel, discussion and dialogue, I have decided to be a candidate for the Democratic nomination for president," he wrote in the email, highlighting economic inequality, climate change and the Citizens United Supreme Court decisions as key issues spurring him to run.
Sanders first confirmed to the Associated Press in a story published Wednesday that he plans to run for the Democrats' 2016 presidential nomination.
"People should not underestimate me," Sanders told The Associated Press. "I've run outside of the two-party system, defeating Democrats and Republicans, taking on big-money candidates and, you know, I think the message that has resonated in Vermont is a message that can resonate all over this country."
Sanders caucuses with the Democrats in the Senate but is an unlikely candidate for the Democratic nomination, primarily because he has never been a registered member of the party and calls himself a "democratic socialist."
Yet many of his views fit with the Democratic left, a constituency in which Sanders has found a small yet devout following. Sanders and his top advisers hope that group of voters will propel his dark horse candidacy. Though Hillary Clinton is the dominant frontrunner, many in the progressive left of the party think she's too moderate and are clamoring for a different candidate to support.
For their part, the Democratic National Committee offered a measured welcome of Sanders to the 2016 race on Thursday.
"Sanders is well-recognized for his principled leadership and has consistently stood up for middle class families," DNC Chairwoman Debbie Wasserman Schultz said in the statement. "Throughout his service in the U.S. House and Senate, Bernie Sanders has clearly demonstrated his commitment to the values we all share as members of the Democratic Party."
Sanders' campaign advisers said that while their candidate has announced his plans to run, he won't hold his first campaign rally until May. That event is expected to be in Vermont.
Sanders is an outspoken critic of Wall Street banks and the outsized influence of money in politics and is a supporter of universal health care. He regularly talks about the need to rebuild the middle class and raise taxes on America's highest earners.
"At a time of massive wealth and income inequality, we need a progressive tax system in this country which is based on ability to pay," Sanders said last month in Washington. "It is not acceptable that a number of major profitable corporations have paid zero in federal income taxes in recent years, and that millionaire hedge fund managers often enjoy an effective tax rate which is lower than the truck drivers or nurses."
In interviews before his campaign announcement, Sanders said trade, income inequality and health care would be key tenants of his run. But despite having vocal liberal supporters on these issues, Sanders is a dark horse candidate and has acknowledged that his run will be uphill. A CNN/ORC poll in March found that Sanders has the support of only 3% of Democratic voters.
Born in Brooklyn, New York, Sanders moved to Vermont after graduating from the University of Chicago. His first successful run for office came in 1981 when he was elected Burlington's mayor by a mere 10 votes. He was elected as Vermont's at-large member of Congress in 1990 and jumped to the Senate in 2007. Sanders is the longest-serving independent in congressional history.
Sanders does not have the personality of a typical politician. He is sometimes gruff and blunt, dispensing with social niceties and usually getting right to the point. He has come to be known as much for his fly-away hair as his passionate speeches in the Senate -- and has bluntly lamented the way political journalism in the United States focuses on personality.
"I think this is not about personality," Sanders told CNN earlier this year, raising his Vermonter-by-way-of-New York voice. "I am not a singer, I am not a dancer, I am not an entertainer."
He also starts with a small campaign infrastructure, largely the remnants of his past Senate runs, and is primarily being advised by Tad Devine, a Democratic political consultant who worked on the presidential campaign for Al Gore in 2000 and John Kerry in 2004. At an event this month in New Hampshire where Sanders leaned heavily into a presidential bid, the signs outside the house party touted his 2012 Senate re-election bid.
From the outset of his campaign, it appears money will be Sanders' biggest issue. The senator has regularly conceded in the last month that he would not be able to raise near the money Clinton will bring in.
"To run a credible campaign in this day and age, you do need a whole lot of money," Sanders said. "Whether the magic number is $200 million, it is $150 million, it is a lot of money, but even with that, you would be enormously outspent by the Koch Brother candidates and the other candidates who will likely spend, in the final analysis, over $1 billion, if not two."
Despite being a champion for many on the left, Sanders has been somewhat left out in the cold by big liberal organizations like MoveOn.org and Democracy for America, who have spent the last few months unsuccessfully urging Massachusetts Sen. Elizabeth Warren to run for president.
"Obviously one would hope one would have as much support as possible from all walks of life," Sanders said on Tuesday when asked why he thinks those groups aren't rallying around him. "I am a great fan of Elizabeth and as for what people do and why they don't do it, I am not going to speculate."
Anna Galland, executive director of MoveOn.org Civic Action, even mentioned Warren in touting Sanders' jump into the race.
"MoveOn members welcome Sen. Bernie Sanders to the presidential race," said Galland. "The Democratic Party is made stronger by each additional voice who enters the race and commits to being a strong advocate for everyday, hardworking Americans and not just the wealthy few. That's why we and our allies continue to call on Sen. Elizabeth Warren to also bring her tireless advocacy for middle-class and working Americans to the race. Our country will be stronger if she runs."
Sanders enters a race that has so far been dominated by Clinton, the former secretary of state and Democrats' prohibitive favorite for the nomination. For most of 2015, Sanders has been reticent to attack Clinton, but he recently has issued statements calling on her to change her policy positions.