While one would think that the rules place a heavier burden on the filibustering party, the rules of the senate actually place a heavier burden of the GOP, a burden that requires that the GOP have a great deal of discipline and fortitude.
The rules regarding filibuster are certainly onerous on the senator trying to maintain the floor and this onus would be problematic if only one senator was seeking to filibuster a bill back in the days before the advent of cloture petitions. However, when a group of 40 to 45 senators with the backing of its party leader seeks to filibuster, the pressure of a 24/7 situation can be evenly distributed on the shoulders of its members.
The party seeking to break the filibuster must do more than obtain 60 votes to invoke cloture, they must jump particular procedural hurdles during a 24/7 situation. In that 24/7 situation, the filibustering party need only keep one, at most two senators on the floor at a time during a filibuster.
However, the rules of the senate allow a senator to suggest the absense of a quorum at any time. Such a motion cannot be debated and is not subject to a vote. The presiding officer must direct the clerk to call the roll. If there are not at least fifty-one senators present after the roll call, the chair must immediately adjourn the senate until the next day. Adjournment is not subject to debate or vote, undermining the purpose behind a 24/7 status in the first place.
If the GOP wants to force the Dems into a 24/7 mode and avoid adjournment, it has to be committed to having all of its senators available in their offices or the cloakroom 24/7 to respond to the inevitable quorum call at 3:30 on a Sunday morning. Meanwhile, the Dems need only keep a rotating skeleton crew of senators available to hold the floor and to act as sentries if the GOP tries to make a parliamentary move.
As such, the rules actually place a heavier burden on the party seeking to break the filibuster than the party seeking to maintain it.
Given the rules and the onus placed on the party seeking to break a filibuster, it would be extremely difficult to keep 51 GOP senators at this level of preparedness for an extended period of time. At this point in time, the GOP only has 4 Dem votes in favor of cloture. And the point of going 24/7 is to bring at least 5 more on board. However, the GOP would only be able to maintain a 24/7 level of preparedness for several days at most.
If the GOP went 24/7 now as it appears stuck at 55, and it came up short of the 60 votes needed after going 24/7 for several days, it would have to beat a retreat, a move that could demoralize some of its forces, particularly the Dems bucking their party leadership, only strengthening the resolve and the position of the Dems and giving little motivation for Dems to cross the aisle.
For these reasons, the 24/7 tactic is only practical when the GOP is very close to getting the 60 votes necessary to invoke cloture. I would say that such a move would be advisable only when the GOP has 58 or 59 votes in favor of cloture.
The second problem facing the GOP is timing. With the headlines focused on the imminent war in Iraq it would appear impossible to get the Estrada filibuster on the front burner of public attention, no matter how egregious the Democrats' tactics have been. By continuing to file for cloture, that could keep the matter ripe for exploitation until the war has abated and public attention and outrage could be directed more effectively to the nomination. In addition, once the war is successfully prosecuted, Bush will no doubt have a more envigorated storehouse of political capital.