(Reuters) - President Barack Obama on Saturday began a broad sales pitch to the U.S. public about the merits of free trade deals, an area in which he faces stiff resistance from many in his own Democratic party.

Obama has said he wants to work with Congressional Republicans to finalize the Trans Pacific Partnership (TPP) trade pact, an agreement that would stretch from Japan to Chile, covering 40 percent of the world economy.

"I’m the first to admit that past trade deals haven’t always lived up to the hype," Obama said in his weekly address. "But that doesn’t mean we should close ourselves off from new opportunities."

The first step in working with other nations to finalize the TPP deal is to pass "fast track" legislation to streamline the passage of trade deals through Congress.

Polling data from the Pew Research Center shows Americans from both parties are skeptical about trade. Only one in five Americans think trade creates jobs, and only 17 percent believe trade leads to higher wages.

Congressional Republicans have been supportive of trade deals. Senator Orrin Hatch, the Republican chairman of the Senate Finance Committee, has said he hopes to introduce a "fast track" bill in February.

Senate Majority Leader Mitch McConnell said in a statement that Obama needed to "continue what must be a sustained effort to move his own party forward" on working on trade legislation.

Labor and environmental groups allied with Democrats have been pushing hard against the idea. Even among the Obama-friendly crowd at the Democratic National Committee on Thursday, several people wore "Stop Fast Track" stickers.

Obama said fast track authority would protect workers and promote businesses, and said exporting companies pay higher wages.

He cast it as a way to push back against the exporting powerhouse of China.

"As we speak, China is trying to write the rules for trade in the 21st century," Obama said. "We can’t let that happen. We should write those rules."

(Reporting by Roberta Rampton; Editing by Clarence Fernandez)