Former Maryland governor Martin O'Malley. (Bruce Smith/AP)

Former Maryland governor Martin O’Malley took another swipe Wednesday at Hillary Rodham Clinton, telling supporters that American workers who could lose their jobs due to a pending trade deal “are owed more than lip service.”

O’Malley’s comments came a day after the Democratic presidential frontrunner hedged on her support for the Trans-Pacific Partnership, which is being pushed by President Obama but is opposed by labor unions and some activists in the Democratic party’s politically potent left wing.

“To me, opposing bad trade deals like TPP is just common sense,” O’Malley says in an e-mail to his supporters, which included an embedded video about his opposition to the deal and a link to a petition drive he is leading on the issue, which is being considered by Congress.

The e-mail makes no direct mention of Clinton, but O’Malley has ratcheted up his rhetoric in recent days as Clinton has been noncommittal about a deal she supported as secretary of state. The subject header on O’Malley’s e-mail is “Hard choice?” — a clear reference to Clinton’s memoir, “Hard Choices.”

“Trade is critical to growing our economy, but fast-tracking TPP means entering into a deal that could depress wages and cost us jobs,” O’Malley’s e-mail says. “That's the last thing we need right now. American workers whose jobs could be on the line right now are owed more than lip service. They deserve to know where leaders stand.”

During a tour Tuesday of a community college in Concord, N.H., Clinton said that “any trade deal has to produce jobs and raise wages and increase prosperity and protect our security.” Her remarks echoed a statement from her presidential campaign late last week.

O’Malley, who lags far behind Clinton in early polling, has said he will make a decision about whether to move forward with a White House bid by late next month.

O’Malley has been maintaining an aggressive travel schedule to early nominating states. He is scheduled to be in South Carolina this weekend and plans to return to New Hampshire on May 13.

Staff writer Anne Gearan contributed to this report.