All 13 Liberal MLAs have signed the letter, which calls on the Harper government to reconsider the new, stricter EI rules.
Opposition Leader Victor Boudreau is asking Premier David Alward and his Progressive Conservative MLAs to sign it as well.
But Deputy Premier Paul Robichaud says the Liberals should have suggested the letter long before the final days of the legislative sitting.
"The reality is, it's a little like Johnny-Come-Lately for the Liberals because they are asking us to sign a letter after the issue's been on the radar screen for six months, and after we brought an Atlantic position on that situation," he said.
The reforms are slated to take effect on Jan. 6.
Boudreau contends if the Tories oppose the changes, they should sign, regardless of the timing.
He says it's important to have a united front against the tough new rules, which include requiring repeat claimants to accept lower-paying jobs farther from where they live.
The letter asks Prime Minister Stephen Harper to provide "greater flexibility recognizing the unique nature of regions where seasonal industries play a significant role in a provincial economy and the lack of full-time employment opportunities.”
The Liberals are offering to rework the letter to accommodate the Tories, said Boudreau.
Both parties agree the federal reforms are bad for New Brunswick. But each party is accusing the other of getting in the way of working together on the issue.
Boudreau continues to inaccurately accuse Alward of flip-flopping on the reforms imposed by his fellow Tories in Ottawa.
"When these changes were first announced Mr. Speaker, he was for them," Boudreau said.
But Alward had said in May, when the changes were announced, that he had concerns. On Wednesday, he adopted a slightly tougher position on the issue. "We don't support a number of the changes in Bill C-38, Mr. Speaker," he said.
Meanwhile, the premier inaccurately accuses the Liberals of just noticing the EI changes.
"The members opposite are finally waking up and realizing it's an issue, Mr. Speaker," Alward said.
However, the Liberals have been pushing Alward since May to be more vocal on the changes.
Under the new rules, announced in May, frequent users of EI must take any job, sooner than they're currently required to. The job could be up to an hour away from home and could pay 30 per cent less than their normal wages.
The reforms could cause problems for many seasonal employers and spur on a further exodus from rural New Brunswick, according to a June 28 briefing note prepared for the premier.
The changes could cut benefits to roughly 465 people during peak periods and reduce the amount of EI benefits flowing into the province by $7 million annually, according to documents obtained by CBC News.
The contentious issue has sparked protests across the province, including one in Shediac earlier this week that attracted about 200 people.
New Brunswick is traditionally one of the the most heavily-dependent provinces on the EI program. In the last 24 months, there were an average of 35,019 EI clients each month, with the number reaching as high as 45,830.Suggest a correction