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MIAMI (CBSMiami) – A rift is growing between Bernie Sanders and the Democratic leadership after his supporters were accused of disrupting Nevada’s Democratic convention.

Now leaders are calling for party unity. A new national poll shows the race for the White house is tightening in a Hillary Clinton/Donald Trump match-up.

Meantime, Bernie Sanders is pushing back against accusations that his supporters nearly came to blows with Clinton backers last weekend in Nevada.

“To suggest that our campaign has anything to with creating violence is an outrage, unacceptable and absolutely insulting,” said Sanders.

Democratic Party leaders said it’s time to unite.

“Everybody needs to take a step back and a deep breath. We have to make sure that we can do everything we can to maximize the likelihood of being unified,” said Congresswoman Debbie Wasserman Schultz.

Hillary Clinton is just 90 delegates shy of winning the nomination but Sanders is vowing to fight all the way to the democratic convention in Philadelphia.

It’s about two and half weeks until the final batch of primaries. Meanwhile, the presumptive GOP nominee is signaling the type of attacks he’d use against Clinton.

A new national poll shows Trump up three points over Clinton in a November election. That same poll showed Clinton with a 7-point lead over Trump in April.

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