The March 1 GOP presidential debate in Georgia has been canceled, in a sign of candidate fatigue after nearly two dozen of the televised showdowns that have been so crucial in shaping the Republican presidential campaign.

CNN confirmed Thursday that it will pull the plug on the debate, the final one before Super Tuesday on March 6, after Mitt Romney’s campaign said he would not take part. Before CNN’s decision, the campaign of Rep. Ron Paul (R-Tex.) said he planned to sit it out, and Rick Santorum’s aides said he was likely to skip it, too.

“Without full participation of all four candidates, CNN will not move forward with the Super Tuesday debate,” CNN said in a statement.

The Republican debates have played a key role in turning the party’s orderly nominating process into a wild and unpredictable ride for candidates. The debates contributed to the failures of former Minnesota governor Tim Pawlenty and Texas Gov. Rick Perry, and helped Rep. Michele Bachmann (Minn.), former Godfather’s Pizza chief executive Herman Cain, and former House speaker Newt Gingrich to seize front-runner status, at least temporarily.

The number of debates has snowballed in the past two presidential elections, in large part because they offer news organizations and sponsors lots of viewers. This year’s GOP debates have been the most-watched on record, topping the debates of 2008 by millions of viewers on average.

It has led to everyone wanting to host a debate, and many have: There were also about two dozen debates in both the Democratic and Republican primaries in 2008.

Although the public has avidly followed the debates, some Republican leaders have worried that candidates have been forced to spend time on debate preparation rather than on building their organizations.

There’s also concern that the debates have ceased to shed light on the candidates, instead turning into a mudfest that could hurt the eventual nominee.

Romney’s campaign got things started by pulling out Thursday afternoon. Within two hours, Paul and CNN had also pulled out.

In dropping out, the Romney campaign cited the 20 debates it had already done.

“Gov. Romney will be spending a lot of time campaigning in Georgia and Ohio ahead of Super Tuesday,” spokeswoman Andrea Saul said in a statement. “With eight other states voting on March 6, we will be campaigning in other parts of the country and unable to schedule the CNN Georgia debate.” ”

Santorum spokesman Hogan Gidley offered a similar explanation for his candidate’s hesitance. “Now is when we need to go out, let people see the vision and meet voters.”

Gingrich’s campaign had said it would still attend the debate before it was canceled.

The debate is in Georgia, the state Gingrich represented in the U.S. House, but Romney and Santorum have signaled that they will compete there. Gingrich, who has relied on debates to keep his campaign afloat, criticized his opponents for dropping out.

“The Romney model is to go to Wall Street and raise huge amounts of money to run negative ads,” Gingrich said. “I understand why having to defend that strategy is not something he’s very happy about.”

Some voters in Michigan were happy to see the debate called off.

Ray Nabozya, a car salesman from Farmington Hills, said he approved of the decisions to skip the Georgia debate.

“I think primary voters know where these guys stand now,” said Nabozya, 54. “At this point, the left is just clearly looking for tape they can use.”

Robert Clark, 68, of Birmingham said a debate between Santorum and Romney might have been helpful. But he said a debate with all four remaining candidates would be the “same old thing” and was not needed.

Both men say they’re voting for Santorum.

There is still a debate set for Wednesday in Arizona, which will now be the last before Super Tuesday. There had been a debate planned for March 5 in California, but it is no longer scheduled.

Staff writers Amy Gardner and Rosalind S. Helderman contributed to this report.