United Parcel Service Inc. (UPS) Chief Executive Scott Davis voiced optimism Tuesday that the recession will end this year, although he also warned protectionism could derail a recovery.

"The biggest declines are behind us," Davis said, speaking during the Detroit Economic Club's National Summit. "2010 will show growth."

Still, he forecast increases in gross domestic product below normal "at least" through 2010, adding he expects growth to be in the 2% to 3% range.

He cautioned as well that the ongoing downturn won't end without the "positive force" of global trade, reiterating his view that "protectionist impulses" threaten the recovery.

"We must argue that protectionism is the worst response at the worst time," Davis told the business executives in attendance. "We can't let political expediency cloud global reality."

He pointed out one in five U.S. manufacturing jobs is linked to global trade, while 57 million Americans work for companies engaged in global trade.

Among other things, he said some of the controversies regarding the North America Free Trade Agreement can be worked out without reopening it. Mexican business groups are contending that the U.S. is violating the agreement by restricting Mexican truck traffic across the border.

The issue "needs to be worked out," Davis said Tuesday. But "the idea of opening up Nafta again, I wouldn't recommend it. Things can be done to solve issues outside of opening it again."

Davis later told reporters UPS is continuing to eye acquisitions, possibly of companies or divisions of companies in Asia or the Middle East, although he stopped short of revealing any potential targets.

UPS shares were up 3 cents, or .06%, in recent trading, at $49.03.

-By Bob Sechler and Jeff Bennett, Dow Jones Newswires; 512-394-0285; bob.sechler@dowjones.com and 248-204-5542; jeff.bennett@dowjones.com