Sen. Bernie Sanders tore into 2020 rival Michael Bloomberg at a Las Vegas campaign event Saturday, saying the billionaire and former New York mayor is trying to "buy the presidency" by paying millions of dollars in advertising.

Why it matters: Bloomberg has surged in national polling recently, having poured millions of dollars into campaign ads largely targeting Trump. His candidacy has become an obvious foil for Sanders, whose grassroots campaign railing against billionaires and the establishment has vaulted him to front-runner status.

What he's saying: At the event, Sanders also said, "We will not create the energy and excitement we need to defeat Trump if that candidate pursued, advocated for, and enacted, racist policies like stop-and-frisk, which caused communities of color in his city to live in fear. We will not defeat Donald Trump with a candidate who in 2015 stated, and I quote: ‘I, for example, am not in favor, have never been in favor of raising the minimum wage.’

We will not defeat Donald Trump with a candidate who opposed modest proposals during Barack Obama’s presidency to raise taxes on the wealthy, while advocating for cuts to Medicare and Social Security. We will not defeat Donald Trump with a candidate who, instead of holding the crooks on Wall Street accountable, blamed the end of the racist policies such as red-lining for the financial crisis. Mayor Bloomberg with all his money, will not create the kind of excitement and energy we need to have the voter turnout we must have to defeat Donald Trump."

— Bernie Sanders, per the WashPost's Dave Weigel

The big picture: Bloomberg is not on the ballot in Nevada, which will host its caucuses next Saturday. He does, however, have a chance to qualify for the Las Vegas debate on Feb. 19, which would mark the first time he and his 2020 competitors would face off in person.

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Editor's note: This article has been updated with more details from Sanders' speech.