CNN

(CNN) - As they fight for momentum on the campaign trail, Hillary Clinton and Barack Obama have also spent the past week-and-a-half dueling it out on the airwaves in multiple Super Tuesday states, to the tune of $2.5 to 3 million each.

The outcome of the Republican contest may be just as uncertain – but no GOP candidate is currently on the air in any of the 21 states that will weigh in on their party’s presidential nomination next Tuesday.

“They made a gamble that someone would have momentum,” says Evan Tracey of TNS Media Intelligence/CMAG, which tracks campaign ad spending. “But no one has captured it. They’re all looking to see what happens in Florida today.”

Currently, just two Republican contenders are reaching viewers in states which vote after Florida’s primary. Mike Huckabee – who is facing a campaign cash crush - has made a less-expensive national cable buy which will also show up in those states. And Ron Paul has purchased airtime in Hawaii, which votes February 19, and his home state of Texas, which weighs in March 4.

–CNN Associate Political Editor Rebecca Sinderbrand