Sen. Bernie Sanders (I-VT) met some stiff resistance during a speech today ahead of the Democratic National Convention in Philly.

Sanders was addressing supporters and was booed loudly and steadily for calling on the crowd to vote for Hillary Clinton.  

He went on to slam Donald Trump, arguing that the GOP nominee must be defeated. 

The tension comes after Democratic National Committee chairwoman Debbie Wasserman Schultz was forced out over leaked emails that appear to show an effort to undermine Sanders' campaign. 

Sanders tried to calm the crowd, referring to them as "brothers and sisters," and saying that this is "the real world." 

"Trump is a bully and a demagogue," he said, adding that Trump's campaign is based on "bigotry and hatred." 

Earlier today, Wasserman Schultz was booed off the stage and heckled this morning at a breakfast for Florida delegates.

Sanders will address the DNC tonight, along with Michelle Obama and fellow Sen. Elizabeth Warren.

Watch the moment above.

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