Bernie Sanders officially joins Hillary Clinton as her only Democratic competition

Mr Sanders has pledged to be tough on the wealthiest 1 percent of Americans

Democratic presidential candidate Bernie Sanders speaks to a crowd through megaphone after a campaign event at New England College on 27 May 2015 in Concord, New Hampshire. (Getty Images)

Vermont Senator Bernie Sanders has organised a rally in Burlington, Vermont to kick-off his political campaign to roughly 5,000 supporters.

Formerly an Independent politician, Mr Sanders will run as a Democrat, and many consider the self-described socialist as the main competition to Hillary Clinton’s campaign. Mr Sanders will run a campaign that’s tough on the wealthiest 1 percent of Americans.

“The gap between the very rich and everyone is wider than at any time since the 1920s," he said at the rally on Tuesday.

"The issue of wealth and income inequality is the great moral issue of our time, it is the great economic issue of our time and it is the great political issue of our time. And we will address it.”

He added: "He’s stated that Clinton’s money would be a challenge to overcome but he said that he’s not fixated on his Democratic competition."

"If I decide to run, I'm not running against Hillary Clinton," Mr Sanders recently told reporters. "I'm running for a declining middle class."

Mr Sanders has received praise from liberal media pundits such as Vox Media’s Ezra Klein and MSNBC’s Rachel Maddow. Mr Klein wrote that Mr Sanders is wildly popular on social media and that he delivers solid policy proposals on large ideas regarding breaking up the biggest banks and moving to a single-payer health-care system.

He also noted that his website already features an “issue section,” while Ms Clinton’s site does not.

Ms Maddow said that he is more than Ms Clinton’s main competition and more than a fringe candidate as he’s “spirited,” “aggressive” and people are very excited to follow his campaign.

“The Beltway media has been treating Bernie Sanders like a gadfly, somebody who exists only to pester Hillary Clinton to move to the left,” she said on her broadcast Tuesday. “But Bernie Sanders … has been bucking that both with his arguments now and with his description of his campaign in the past.”