It's the same thing the Dems were pushing with their questions during the Alito hearings
IMO, we're back to the Carter period when pundits were speculating the Presidency was too big for one man and should be divided between three.
The difference is motive.
Back then Carter had run the Country to the ground, with help of his Liberal friends. Instead of reviewing Carter's (in)competance and their policies, they thought the job had just become too expansive.
With Bush, they resent he's the Executive. It isn't a question of incompetance or failed ideology, rather that on certain key issues he's intractable while Senators are notoriously spineless and can be bent to liberal position far more easily.
Instead of advocating a three person Presidency, because half of the Senators want to be the sole Executive, they want to temporarily suspend the current President's powers for their own. If it's a Republican next, they'll keep the usurped power. If Liberal, they'll (probably) return the power. At least that's their thinking. But my guess is that once Congress had it, they wouldn't return it. No one willingly relinquishes power. Either the Liberals (and RINO's) in Congress desirous of being the Executive don't believe they'll really win any time soon despite rhetoric, or they remain delusional about their ability to reclaim what they take from Bush once becoming the Executive.
However, Bush isn't willingly relinquishing his constitutional authorities and I suspect the next President, either Dem, Rep or RINO will be appreciative those powers remain.