U.S. Senator Bernie Sanders officially launched his bid in the 2016 presidential race on Thursday, promising to fight against "obscene levels" of income disparity in America.

"After a year of travel, discussion and dialogue, I have decided to be a candidate for the Democratic nomination for president," wrote the Independent Vermont senator in an email, according to CNN.

During his campaign, Sanders says he will focus on many of the key issues that he has championed throughout his 16-year career in Congress, including economic inequality, climate change and an overhaul to the campaign finance system, which described as a "real disgrace."

The progressive politician also blasted billionaire big-money donors and other "soap opera aspects of modern campaigns" during a press conference kicking off his candidacy on Thursday.

"I think the American people are tired of that," Sanders said.

The self-described "socialist-democratic" also said he is running to stop the Trans-Pacific Partnership or TPP and change the tax code so that multi-million dollar companies can no longer find loopholes that allow them to avoid paying taxes by storing their money overseas.

"Their responsibilities are not to shift jobs to China, their responsibility is not to avoid paying federal taxes," he said.

"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."

"What we have seen is that while the average person is working longer hours for lower wages, we have seen a huge increase in income and wealth inequality, which is now reaching obscene levels," said the 73-year-old congressman to the AP.

"This is a rigged economy, which works for the rich and the powerful, and is not working for ordinary Americans. ... You know, this country just does not belong to a handful of billionaires."