At that time, Bob Stevenson was a top aide to then-Majority Leader Bill Frist of Tennessee. He described the threat then as an "action-forcing mechanism" that resulted in the creation of the "Gang of 14."
Stevenson warned if Reid employs the nuclear option now it would "dramatically change the very nature and culture of the Senate, spilling over into already poisonous partisan debates down the road and making resolution of those issues even more difficult."
He said he is hopeful, but not optimistic, that when senators meet Monday night, the seriousness of the potential consequences will lead to "cooperation and compromise."
A Democratic aide, who was also at the center of the 2005 fight and who asked not to be identified, said he hopes when the senators meet privately maybe "some of the more seasoned veterans of these battles" will come forward and say "'Isn't there a way to resolve this?' That's what happened in 2005."
McConnell said Sunday that he hoped an ugly fight can be avoided, as it was in 2005 when "cooler heads prevailed."
"We knew it would be a mistake for the long-term future of the Senate and the country. That's what I hope is going to happen here, David," McConnell told NBC's David Gregory. "We have an opportunity to pull back from the brink in this meeting we're going to have of senators in the Old Senate chamber Monday night. I hope we'll come to our senses and not change the core of the Senate."