(CNN) Marco Rubio came in last in every state but his own on Super Tuesday 3, despite spending about twice as much on TV advertising as all of his Republican rivals combined.
The super PAC that supports the Florida senator -- Conservative Solutions PAC -- shelled out $20.3 million in the five states that voted on March 15, but Rubio pulled in less than a million votes. In other words, his 961,334 votes cost about $21.12 each.
That dwarfs the spending of Donald Trump, who doled out the second-largest amount. The billionaire businessman paid about $4.7 million for TV advertising and got 3,190,623 votes. That's a budget-conscious $1.47 per vote.
Rubio dropped out of the presidential race Tuesday night after conceding the Florida primary to Trump.
John Kasich, whose win in his home state of Ohio means he lives to fight another day, spent about $1.63 per vote. The governor's campaign and its supporters paid $2.7 million for TV ads, and he took 1,656,872 votes.
Ted Cruz spent slightly more than Kasich or Trump per vote but came much closer to their cost-effectiveness than to Rubio's. The Texas senator's campaign and allies spent $3.6 million to win 1,896,851 votes, or about $1.90 per vote.
Over on the Democratic side, Hillary Clinton's victory was comprehensive: She won at least four of the five states (Missouri is still too close to call) and spent less than Bernie Sanders doing it.
Clinton and her allies coughed up $9.4 million in TV ads and the former secretary of state took 3,700,666 votes. That works out to $2.54 per vote.
The Vermont senator spent $10.5 million in ads and got 2,354,056 votes. That's a cost of $4.46 per vote.
TV advertising spending estimates come from CMAG/Kantar Media and cover spending in Florida, Illinois, Missouri, North Carolina and Ohio from January 1, 2015 to March 15, 2016.