Conservative senators say they want to enforce Canada's legislation for work on Sunday, but point their finger to independent senators for postponing the third and final reading Monday.
The House of Commons submitted the bill earlier this week and pushed it quickly, and then asked the Senate to do the same.
Conservative Senator Leo Hawacos said his house told the Independent Senator Group (ISG) that they were ready to sit on Sunday to hand over Bill C-89 as soon as possible.
"We have offered our full cooperation to read, import and pass [Sunday] afternoon, "said Hawacos in an interview with CBC News.
After nearly eight hours of research in a rare weekend on Saturday, the Senate agreed to hold the third and final reading of the bill Monday afternoon.
But Huakos said the majority of the upper house was ready to sit on Sunday, while several ISG members blocked the offer.
"They had members in their cabin that were not in and would not give leave [to immediately proceed with the final reading]. "
Members of the Canadian Post Workers' Union (CUPW) have held rotational interruptions for more than a month, causing the accumulation of unsorted mail and packages at post offices.
The controversial bill for returning to work, if adopted, will enter into force at noon on the day following the King's approval.
Watch: Patty Haywood explains the need for legislation to work backwards
When ISG leader Peter Hardard requested a unanimous agreement to proceed to the third reading of the bill, several Senators voiced their opposition.
Senator Yuen Pau Wo, a member of the Independent Group, said he opposed the overhaul of the Bill too quickly to assess both sides of the postal debate.
"We heard contradictory testimony by witnesses, which makes it difficult for us to get an accurate picture of what is happening." I am happy to have a day for reflection before we repeat the debate on Monday, "Wo said in an e-mail.
"We act in a hurry but we do not act in a hurry."
Festivals are fast approaching
On Saturday, the senators have heard of Canada's provisional president and the head of the union.
"I did not want to discuss legislation to get back to work," says Jessica McDonald of the Canadian Post.
"Despite the enormous efforts … we have failed to find the necessary common ground."
Watch: The Canadian Post Strike in Monton
CUPW President Mike Pelechek shared numerous stories about workers who were injured at work or who worked so long overtime that they barely see their families.
For his part, Housakos emphasized his support for the bill because the holidays are coming and Canadians will rely on postal services to deliver packages.
"This will have a devastating impact on the Canadian trade industry, which is largely dependent on Christmas sales," he said.
Union leaders have repeatedly argued that the law violated their collective bargaining rights.
In 2011, then the conservative government adopted labor laws requiring the cessation of Canada's blockade and the withdrawal of postal strikes.
But this legislation was abolished by the courts in 2015 after it ruled that by abolishing the right of workers to strike, the bill violated their right to freedom of association and expression.
The current liberal government, on the other hand, believes they have drafted the bill in a way that does not violate charter rights as it does not impose immediate results affecting postal contracts.
Husakos said existing legislation could be revoked, but he reiterated that his main concern is to ensure that mail is delivered.
"More importantly, make sure the trucks are moving, the mail is delivered and the Canadian economy and the Canadian public are served."
CUPW has already vowed to fight the court law that Housakos has said they have the right to do.
Meanwhile, the negotiators on both sides stayed at the negotiating table on Sunday in a final effort to bring an immediate end to the rotating attacks, but with little sign that an agreement will be reached before the Senate returns for the last reading.
Senators must return for third reading on Monday at 14:00. ET.
With Canadian prints