"The attack on workers is heating up," Ken Lewenza told a CAW convention in referring to the proposed merger with the Communications, Energy and Paperworkers Union of Canada.
"Again collective bargaining is being strangled and unions are being targeted. The downward pressure on wages and other forms of compensation is staggering."
Lewenza said federal intervention in negotiations involving CP Rail (TSX:CP), Canada Post and Air Canada (TSX:AC.B) workers had been an attack on workers' rights.
Meanwhile, the government's move to change rules around employment insurance is an attempt to "bully and punish" workers who have lost their jobs, the CAW president said.
His remarks came at the CAW kicked off its constitutional and collective bargaining convention in Toronto with songs and a procession of more than 400 retired autoworkers.
On Wednesday, delegates will vote on a proposal to merge with CEP, a move that key players have said would revitalize the labour movement.
Lewenza said it will be hard for the CAW to change its name if it accepts the proposed merger.
"To a certain degree there are pockets of people that fear change, but geez, if you fear change, that's not in the interest of our members," he said.
"I think the merger will go through and I think we'll have a combined convention next year."
The new union would represent more than 300,000 workers across roughly 20 economic sectors. Most of the membership would be concentrated in manufacturing, communications and transportation.
CEP delegates will vote on the proposal when they meet in October.
The CAW began contract talks with the big U.S. automakers — GM, Ford and Chrysler — last week.
The union, which made concessions on wages, vacation time and other benefits when the U.S. automakers were struggling during the 2008-09 recession, has said it wants to share in the profits now that the industry has rebounded.
The automakers have said their focus during the negotiations will be to improve competitiveness at their Canadian operations, where labour costs are higher than in the United States.
Note to readers: This is a corrected story. An earlier version said union members would vote on the merger proposal.