The Senate won't take up its coronavirus relief bill until Thursday, as Democrats wait to get the green light that the legislation complies with arcane budget rules.  

The chamber had been expected to vote to proceed to the sweeping $1.9 trillion bill on Wednesday, but a Senate Democratic aide said they are still waiting for guidance from the Congressional Budget Office (CBO) that it complies with reconciliation rules that let them bypass the 60-vote filibuster. 

The Senate then subsequently wrapped until noon on Thursday afternoon.  

“They think they need several hours. That’s why they’re coming in at noon, to give them a little flexibility,” said Sen. Dick Durbin (D-Ill.), asked if there was an expectation that they would have the CBO score by noon.  

Democrats will just need a simple majority to get over the initial procedural hurdle. 

But even after then it could be hours, or potentially days, before they get to a final vote on the coronavirus bill. 

“It will come to an end. I don’t know if it will be one day or five days," Durbin added. 

Sen. Ron Johnson (R-Wis.) is planning to force Senate staff to read the entire coronavirus bill on the Senate floor, a process that senators predict could take up to 10 hours.  

"When they offer the substitute amendment we can ... object to waiving the reading of the bill," Johnson said.  

Johnson also hinted that he could force every amendment to be read during the vote-a-rama, telling reporters: "I think that'd be a good idea." 

Even after Democrats overcome Johnson's roadblocks — which won't sink the bill, but will slow down a final vote — they still face an additional 20 hours of debate. 

Durbin indicated that Democrats could yield back 10 of those hours, though he stepped short of saying they would give back all of their time. 

"After the 20 hours is up or there is agreement to move things up, the Senate would proceed to vote-a-rama," the Senate Democratic aide added.

If Johnson forces the entire Senate bill to be read and the 20 hours of debate time is used up, that would mean the Senate wouldn't start the marathon voting session known as vote-a-rama — where any lawmaker can force a vote — until early Friday evening. That's assuming they stay in session around the clock. 

Even after that senators are likely to file hundreds of potential amendments to the sweeping $1.9 trillion coronavirus legislation. A previous vote-a-rama to the budget resolution, which teed up the COVID-19 relief bill, started in the afternoon and didn't wrap up until after 5 a.m.  

GOP senators are warning that the upcoming marathon session will be lengthy, and likely longer.  

“I would expect a very long night into the next day and keep going on. A lot to still cover," said Sen. James Lankford (R-Okla.).  

Sen. John Cornyn (R-Texas) added that "I think it probably will go longer than what you saw with the budget resolution." 

"I think people realize that this is an opportunity to offer amendments that they want to offer, so I think we're going to be here for a while," he said.