BEIJING — The Trans-Pacific Partnership trade deal was welcomed on Tuesday as a win for the United States in its contest with China for clout in Asia, as America’s allies expressed optimism about the impact of the 12-nation accord on a region worried about its dependence on the slowing Chinese economy.

The pact still must win approval in Congress, and analysts said the economic effects may be less sweeping than Washington predicts. But the mere fact that President Obama delivered on his pledge to close the deal came as a relief to allies in Asia. It was seen as a counterweight to China’s efforts to expand its influence not just in trade but in other areas, including its island-building in the disputed South China Sea and the establishment of a new regional development bank to compete with Western-led institutions.

“The TPP may not be the game-changer the Americans say it will be, but if the TPP failed, it would certainly have been a blow to U.S. credibility, and its conclusion is to be welcomed,” said Bilahari Kausikan, a former permanent secretary of Singapore’s Foreign Ministry. Yet, he cautioned: “This is not going to erode what China does.”

Image President Obama said Tuesday that the trade deal created "a level playing field" for American goods. Credit... Stephen Crowley/The New York Times

The victory for the United States comes as China’s position in Asia has been thrown off balance by questions about the condition of its economy, which is expanding at its slowest pace in a quarter century and has sent tremors across the region. Even with the slowdown, though, the Chinese economy is growing faster than those of most industrial nations, and China enjoys deepening economic ties with almost all countries in the region.