WASHINGTON — The release on Thursday of the full text of President Obama’s trade accord with 11 Pacific Rim nations brought out opponents and supporters and officially opened what may be the last big battle of the president’s tenure: winning congressional approval of the largest regional trade deal in history.

The opposition mainly came from the left, as an array of unions, environmental groups and public advocacy organizations that typically resist global trade agreements registered their dismay. But some businesses, like Ford Motor, also joined the emerging resistance to the Trans-Pacific Partnership.

The reaction confirmed that in this final fight, Mr. Obama will have to rely on the Republicans who control Congress if he is to sell the legacy-making agreement in the months before the House and Senate vote next spring. Republican leaders were withholding endorsements for now, leaving the president to make the case on his own.

Mr. Obama immediately sought to do so. Early Thursday, the White House posted the text of the deal on Medium, a social media sharing website, along with the president’s statement hailing the agreement as a “new type of trade deal that puts American workers first.”