Canadian postal workers are prepared to strike at midnight Thursday if they don't get anywhere with their latest contract demands and the government doesn't ease up on its own, the union says.

If there is a strike, delivery of everything except Old Age Security and other federal cheques could stop.

On Monday, the Canadian Union of Postal Workers tabled a "new and final offer," which included a lower wage demand among other revisions, chief negotiator and national president Denis Lemelin told a news conference in Ottawa.

"We're still pushing for a collective agreement, but at the same time Canada Post has to recognize they have to let go of their demands and rollbacks," Lemelin said, citing management proposals for lower wages and vacation benefits for new employees.

The union gave the government the required 72 hours' notice of a strike, meaning postal workers could begin withdrawing services at 11:59 p.m. Thursday.

Deadline could help negotiations

But Lemelin, recalling past last-minute contract settlements with Canada Post, said the union is willing to negotiate until the deadline to avoid a strike.

Canada Post, which has offered pay increases that would lead to a top rate of $26 an hour, called the union "out of touch" with the challenges facing the Crown corporation. Among these are a 17 per cent drop in mail volume since 2006.

Canada Post also said in a news release that the union's demands would cost almost $1.5 billion over four years.

Lemelin dismissed the corporation's economic arguments.

"We made that corporation profitable for the last 16 years," he told the CBC's Evan Solomon on Power and Politics.

And while the volume of mail may be down, the number of homes and businesses that get mail delivery increases every year, Lemilin said.

The union, which represents close to 50,000 letter carriers and other workers, has been negotiating with the government for more than seven months. Sick leave and pensions are also issues.

The union is asking for a four-year contract with wage increases of 3.3 per cent in the first year and 2.75 in years two and three. The average starting wage for postal workers is $23 an hour.

Canada Post's offer includes a defined benefit pension plan for both new and existing employees, up to seven weeks vacation and job security.

Last strike was in '97

Postal workers last went on strike in 1997, when they were legislated back to work. For  many Canadians, hard-copy mail has come to seem almost quaint and unnecessary since then.

Still, in its last annual report, for 2009, Canada Post said it delivered about 11 billion pieces of mail to 15 million residential and business addresses.

Jon Hamilton, a spokesman for Canada Post, suggested Monday that the union hasn't grasped the competitive pressure or the risk of losing even more business because of a strike. Many businesses and individuals still depend on conventional mail, and this is a "critical time" for the corporation, he said.

"Even the threat of a strike causes uncertainty for businesses," Hamilton said.

Lemelin said the union has advocated an expansion of Canada Post services to make it more competitive. The union would like to see, for example, the introduction of banking for customers, which other countries have established at their postal outlets.