Hillary Rodham Clinton said Wednesday that she will likely oppose the sweeping Pacific trade deal negotiated by the Obama administration and announced this week, a notable departure from the White House on one of the president's signature achievements.

Clinton, the front-runner for the Democratic nomination for president, staked out her position against the deal under increasing pressure from organized labor to join unions in their opposition. Battling the Trans Pacific Partnership, as the pending agreement is known, has been a top priority for progressives.

In an interview with "PBS NewsHour" to air Wednesday evening, Clinton said, "I don't believe it is going to meet the high bar I have set." She also said: "I am not in favor of what I have learned about it."

While Clinton hedged her opposition to the deal, her comments are probably unwelcome at the White House amid its aggressive push to finalize the pact.

Clinton's team notified the White House of her plans to oppose the deal, an official there said, declining to comment further on what was labeled a private conversation.

"I have been trying to learn as much as I can about the agreement, but I am worried," Clinton said in the "NewsHour" interview. She warned that the agreement does not deal with the issue of currency manipulation, and that "pharmaceutical companies may have gotten more benefits and patients and consumers fewer" in it.

"There are still a lot of unanswered questions," she said.

Clinton, who has been a champion of other such trade deals, reflected on how they have not always had the intended effect.

"We've learned a lot about trade agreements in the past years," she said. "Sometimes they look great on paper. I know when President Obama came into office, he inherited a trade agreement with South Korea. I, along with other members of the Cabinet, pushed hard to get a better agreement. We made improvements. Now, looking back on it, it doesn't have the results we thought it would."

Other presidential candidates have had harsh words about the agreement. Clinton rival Bernie Sanders, the Vermont senator, has used his early opposition to the agreement in building a formidable coalition of support for his candidacy.