A group of top national polls released this week show Bernie Sanders in control of the 2020 Democratic race ahead of Wednesday's debate in Las Vegas.

The state of play: Joe Biden, who has been at the top of the polls for months, plunged after lackluster performances in Iowa and New Hampshire — allowing Sanders to surge ahead as billionaire Mike Bloomberg has cut into the former vice president's lead among moderate voters.

The results

Washington Post-ABC News:

NBC News-Wall Street Journal:

NPR-PBS NewsHour-Marist:

Sanders: 31% (up 9% since December)

Bloomberg: 19% (+15%)

Biden: 15% (-9%)

Elizabeth Warren: 12% (-5%)

Amy Klobuchar: 9% (+5%)

Pete Buttigieg: 8% (-5%)

What to watch: The Nevada debate marks the first time Bloomberg has qualified and will be on stage with the rest of the contenders.

His rivals plan to curb his rise by painting him as a Democratic version of PresidentTrump — an egomaniac New York billionaire who's stained by sexism and racial slights, and hell-bent on buying power and puppeteering mass media, write Axios' Jim VandeHei and Mike Allen.

Worth noting: Because the primary process is conducted on a state-by-state basis, national polls often have their limitations, but these results from three major pollsters crystallize the trend lines currently at play in the race.