CNN canceled its March 1 Republican presidential debate on Thursday after three of four candidates declined to participate, citing busy campaign schedules leading to Super Tuesday on March 6.

"Mitt Romney and Ron Paul told the Georgia Republican Party, Ohio Republican Party, and CNN Thursday that they will not participate in the March 1 Republican presidential primary debate," CNN said in a statement. "Without full participation of all four candidates, CNN will not move forward with the Super Tuesday debate."

Former U.S. Sen. Rick Santorum also said he would not participate, leaving only former House Speaker Newt Gingrich committed to attending.

Still scheduled is a Feb. 22 debate sponsored by CNN and the Arizona Republican Party in Mesa, Ariz. It will be moderated by CNN's John King.