President Barack Obama made a rare last-minute appearance on Capitol Hill on Friday in an attempt to win over the large majority of House Democrats who are hesitant to back his signature trade agenda.

The closed-door emergency caucus meeting came just hours before lawmakers are set to vote on legislation central to the president's legacy-building Pacific Rim trade accord, reported The Associated Press.

The House on Friday will take up two critical measures already passed by the Senate - the Trade Adjustment Assistance (TAA) and the Trade Promotion Authority (TPA). The first bill would provide aid to workers who lose their jobs due to free trade deals, including job retraining, relocation allowances and help with health care expenses. The second would give Obama and future presidents fast-track authority to negotiate the Trans-Pacific Partnership, meaning the international trade accord could not be amended or filibustered by Congress, according to The New York Times.

But unless Obama is able to shore up more support among his own party, those measures are expected to fail.

So far, only about 20 Democrats are publicly in favor of TPA, reported USA Today. While Democrats have historically backed such agreements, lawmakers complained to White House officials this week that the package isn't generous enough. By opposing it, many see an opportunity to bring down the entire trade package, according to Politico.

House Minority Leader Nancy Pelosi, D-Calif., has yet to say whether she will vote for either measure, while House Minority Whip Steny Hoyer, D-Md., has said he will vote for TAA, but hasn't decided on TPA. Assistant Democratic leader Rep. Jim Clyburn, D-S.C., is also undecided, according to Politico.

Republicans, on the other hand, have forged an unusual alliance with Obama on the trade deal.

Obama left the meeting after about 35 minutes, and while he was smiling, he seemed circumspect about whether he made progress, according to Reuters. "I don't think you ever nail anything down around here. It's always moving," Obama told reporters as he exited the meeting.

Some Democrats who had already decided to vote against the trade measures said Obama failed to change their mind, while Rep. Steve Israel of New York said he believes Obama's persuasiveness "secured some votes inside that room," reports Reuters.

The Obama administration will likely need more than two dozen Democratic votes to make up for Republican defectors, according to The Washington Post.