In her first detailed comments on the trade deal since the House of Representatives refused on Friday to allow Mr. Obama to negotiate it freely, Mrs. Clinton laid out a far more calibrated position on the deal than many Democrats and Republicans have taken. She declined to take sides on the Friday vote itself but instead allied herself with Democratic critics of the deal — without actually opposing it.

She argued that the House vote gave Mr. Obama “this amazing opportunity” to seek concessions from Pacific trading partners to salvage the deal.

“The president should listen to and work with his allies in Congress, starting with Nancy Pelosi, who have expressed their concerns about the impact that a weak agreement would have on our workers to make sure we get the best, strongest deal possible,” Mrs. Clinton said at a rally here.

“And if we don’t get it, there should be no deal,” she added.