Bernie Sanders' presidential campaign has spent $3.4 million on advertisements in this week's contests, including $1.3 in Arizona (which holds its primary today) and $1.4 million in Washington (which holds its caucuses on Saturday), according to ad-spending data from SMG Delta.
By contrast, Hillary Clinton's campaign has spent $600,000 in just one state - Arizona.
Overall this campaign season, the Sanders campaign has outspent the Clinton camp in ads, $42 million to $36 million.
On the Republican side, the Ted Cruz campaign and allies have spent a combined $980,000 in Arizona and Utah, while Donald Trump's campaign has spent $518,000 in those two states.
Arizona (March 22)
Sanders: $1.3 million
Cruz: $615,000 (from both campaign and Super PAC)
Idaho (March 22)
Utah (March 22)
Cruz: $364,000 (from both campaign and Super PAC)
Hawaii (March 26)
Washington (March 26)
Sanders: $1.4 million
SOURCE: SMG Delta/NBC News