Late Tuesday afternoon CNN announced an amendment to the rules for its debate scheduled for September 16.

CNN’s original rules included time-specific polling data that did not accurately mirror current GOP primary field standings. In particular, Carly Fiorina’s rapid rise in the polls.

Last week, a spokeswoman from CNN said the network would not yield to candidate complaints, saying:

“Our criteria are totally appropriate and we have been absolutely transparent about them throughout. If the Fiorina campaign had an issue with them they could have raised it when we published them in May. They did not,” the spokeswoman said. “Revising the criteria on the eve of the debate at the demand of and solely for the benefit of one particular candidate is not something we have done in the past, and we will not do it now.”

Mounting pressure from news outlets, public figures, and Carly Fiorina’s campaign seems to have caused CNN to reconsider.

The network explained that a lack of national polling data was to blame. With a significantly greater number of national polls taken during the same timeframe in previous election cycles, CNN claims they had no reason to believe this cycle would have rendered a polling deficiency.

Rather than look to national polling averages in data collected from July to September, CNN has amended the debate qualification criteria so that rankings will be decided based on polling data released from August 7 to September 10.

CNN reports:

CNN is amending the criteria for its Republican presidential debate on September 16, possibly opening the door for Carly Fiorina to join the other top-tier candidates on the stage.

The cause: a lack of national public polling following the August 6 debate has so far provided only three new polls to determine the lineup for the Reagan Presidential Debate, according to a CNN statement.

As a result, CNN reevaluated its criteria and decided to add a provision that better reflects the state of the race since the first Republican presidential debate in August, the network announced Tuesday.

Now, any candidate who ranks in the top 10 in polling between August 6 and September 10 will be included.

The adjustment may result in additional candidates joining the top-tier debate, but the final podium placements will not be known until the eligibility window closes on September 10.

“In the event that any candidate is polling in the top 10 in an average of approved national polls released between August 7th and September 10th, we will add those candidates to our top tier debate, even if those candidates did not poll in the top 10 in an average of approved national polls between July 16th and September 10th,” CNN said in a statement. “We have discussed these changes with the Republican National Committee and the Ronald Reagan Presidential Library, and they are fully supportive.”

…CNN, which is telecasting the Republican National Committee-sanctioned debate, released criteria for the debate May 20 that outlined specific polls and a timeframe to determine eligibility for this event. As of Tuesday, only three polls recognized by CNN have been released, and it appears there will not be enough to make a fair editorial judgment before the September 16th debate, according to the network.

The network said that from August through mid-September 2007, there were 16 polls released. During the same period in 2011, 15 polls were released. Based on previous poll releases, CNN created its original criteria.

“In May, we announced criteria for our September 16th Republican debates at the Ronald Reagan Presidential Library,” CNN said in a statement. “We said that we would use the average of approved national polls from July 16th through September 10th to determine the makeup of the debates. At the time, we expected there to be many more national polls following the first Republican debate, in August, than there appears there will be.”

CNN continued, “We learned this week that there will likely be only two more polls by the deadline of September 10th. In a world where we expected there to be at least 15 national polls, based on historic precedent, it appears there will be only five. As a result, we now believe we should adjust the criteria to ensure the next debate best reflects the most current state of the national race.”

Meanwhile, in camp Fiorina:

As with the Fox News debate, there will also be an earlier debate for GOP contenders not making the top 10 cut off.

Follow Kemberlee Kaye on Twitter @kemberleekaye