MANILA, Philippines — When President Barack Obama gathered his partners in a new trade deal to celebrate finalizing the massive accord, the group posed for a fast photograph, shook some hands and got back to work.

Such is the nature of Obama’s trade tour through Asia this week. Even as he marks a major milestone on the world stage, Obama is looking at a tough fight over ratification at home.

“Execution is critical,” Obama told the 11 other Pacific Rim leaders on Wednesday as they met for the first time since completing the Trans-Pacific Partnership. Obama urged the group ratify the deal as quickly as possible.

The U.S. is likely to drive the pace.

Trade legislation passed last summer prevents Obama from even formally signing the deal until January. Mandated studies and other procedural requirements push the window for a vote squarely into campaign season — or perhaps even after the election.

The president is facing opposition to the deal, the cornerstone of his effort to “rebalance” U.S. foreign and economic policy toward Asia, from Democrats and Republicans alike. Many Democrats, labor groups and the party’s presidential candidates — including Obama’s former Secretary of State Hillary Rodham Clinton — argue the deal will lower wages and includes weak environment and labor standards. Some Republicans, including some with free-trade records, have signaled they’re not inclined to hand Obama a major victory in an election year.

“Whether you can get the votes essentially comes down to whether Republicans like trade more than they dislike Obama,” said Daniel Bob, analyst at Sasakawa USA, a think tank that studies U.S.-Japan relations.