Outside groups have spent $11 million in advertisements attacking Donald Trump in the March 15 primary states of Florida and Illinois, according to ad-spending data from SMG Delta. In Florida, the groups American Future Fund, Club for Growth and Our Principles PAC have spent a combined $4.2 million against Trump -- in addition to the estimated $4.3 million that Marco Rubio's Super PAC, Conservative Solutions PAC, has aired versus Trump. RELATED: Meet the Republican leaders publicly opposing Trump By contrast, Trump's campaign has fired back by spending $1.5 million in Florida. In Illinois, American Future Fund, Club for Growth and Our Principles PAC have spent $2.5 million against the GOP frontrunner. On the Democratic side, Hillary Clinton is outspending Bernie Sanders in the March 15 states of Florida and Illinois, while Sanders is outspending Clinton in Missouri, North Carolina and Ohio. SOURCE: SMG Delta This story originally appeared on NBCNews.com.