(CNN) -- What key constituency group are the presidential candidates fighting over? Soccer moms? NASCAR dads? Perhaps, but if television ad spending habits are any indication, the keys to the White House may be held by Pat Sajak and Vanna White.
Sens. Hillary Clinton, Barack Obama and John McCain have bought ads on "Wheel of Fortune."
Over the course of the campaign, presidential candidates Sens. Hillary Clinton, Barack Obama and John McCain together have spent more than $2 million to air campaign ads on "Wheel of Fortune," the long-running syndicated game show on which Sajak and White are the hosts.
That's more than the three have spent on any other individual television program, according to data from TNS Media Intelligence/Campaign Media Analysis Group or CMAG, CNN's consultant on political ad spending.
" 'Wheel of Fortune' is a great way to talk to typical American voters in an efficient way," said Evan Tracey, CMAG's chief operating officer. "It's a program that typically follows the news and leads into prime time, so it's inexpensive but also efficient."
Running a close second to "Wheel" is "The Oprah Winfrey Show." Obama, who received Winfrey's endorsement last year, has bought an estimated $974,000 in ads on the Chicago, Illinois-based talk show, compared with $596,000 for Clinton and $185,000 for McCain.
But when considering a category of show rather than an individual program, the biggest recipients of presidential TV ad dollars are the hundreds of local news broadcasts in cities across the country.
The three presidential candidates have spent a combined $36.7 million on the local news, with Clinton edging Obama in spending there, $17 million to $16 million. McCain has spent almost $4 million on local news since the start of the campaign.
Clinton also spent big chunks of TV advertising money on morning network news programs: NBC's "Today Show" and ABC's "Good Morning America." Obama's top five television programs in terms of ad spending were rounded out by "Today" and the CBS sitcom "Two and a Half Men," while McCain also spent big on the syndicated show "Jeopardy," and NBC's "Deal or No Deal." E-mail to a friend