U.S. Democratic presidential candidate Hillary Clinton said on Wednesday she does not support the 12-nation Trans-Pacific Partnership (TPP), rejecting a central element of President Barack Obama's strategic pivot to Asia that she helped shape as secretary of state.

She said during a campaign swing in Iowa that she is worried about currency manipulation not being part of the agreement and that "pharmaceutical companies may have gotten more benefits and patients fewer."

"As of today, I am not in favor of what I have learned about it," Clinton said in a "PBS NewsHour" interview recorded during a stop at Cornell College in Mount Vernon, Iowa. "I don’t believe it’s going to meet the high bar I have set."

She helped lay the foundation for the deal as Obama's secretary of state. In 2012 she lauded the TPP as setting “the gold standard in trade agreements to open free, transparent, fair trade, the kind of environment that has the rule of law and a level playing field.”

She joins Democratic rivals Bernie Sanders and Martin O'Malley, who warn the trade deal could lead to lost American jobs.

The TPP deal, reached on Monday after marathon talks among the United States and 11 other Pacific Rim nations, aims to liberalize commerce among those countries, which account for 40 percent of the world's economy. The deal, which must be approved by Congress, has faced skepticism from lawmakers.

Many Democrats, including labor groups whose support Clinton is seeking, fear the pact will cost manufacturing jobs and weaken environmental laws.

"I have said from the very beginning that we had to have a trade agreement that would create good American jobs, raise wages and advance our national security," she said on Wednesday.

"I think there are still a lot of unanswered questions, but for me, it really comes down to those three things," she said.

Al Jazeera and wire services