Four days until Nevada’s Democratic caucuses, Hillary Clinton is now outspending Bernie Sanders over the state’s airwaves — a reversal from a week ago, according to the latest ad-spending numbers from SMG Delta.

Team Clinton has spent $3.3 million on Nevada ads, while Sanders has spent $3.2 million. Last week, it was Sanders at $1.9 million and Clinton at $1.5 million.

Meanwhile, for the Feb. 27 South Carolina Democratic primary, Team Sanders has spent $878,000, versus Team Clinton’s $712,000.

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In the Republican race, Jeb Bush’s Super PAC and campaign have spent nearly $13 million in ads for this Saturday’s South Carolina primary on Feb. 20 - followed by Marco Rubio and his allies at $11 million in the state, Ted Cruz at $8 million and Donald Trump at $1.3 million.

Overall, more than $262 million has been spent on ads in the 2016 presidential race, and the biggest advertiser has been Team Bush at nearly $81 million. That’s followed by Team Rubio at $50 million-plus, Team Sanders at $25 million and Team Clinton at $20 million.

The biggest overall ad spenders

Team Bush: $80.9 million

Team Rubio: $50.4 million

Team Sanders: $25 million

Team Clinton: $20 million

Team Cruz: $16.8 million

Team Trump: $8.5 million

The biggest South Carolina ad spenders

Team Bush: $12.8 million

Team Rubio: $11.1 million

Team Cruz: $8.1 million

Team Trump: $1.3 million

Team Sanders: $878,000

Team Clinton: $712,000

Team Carson: $696,000

The biggest Nevada ad spenders

Team Clinton: $3.3 million

Team Sanders: $3.2 million

Team Rubio: $560,000

SOURCE: SMG Delta/NBC News

This article first appeared on NBCNews.com.