House Republicans are moving forward with a new plan to save President Obama’s trade agenda that will likely rely on whether GOP leaders can win the trust of moderate Democrats who want assurances that aid for workers will be part of the final legislative package.

The process will kick off on Thursday when the House is set to vote on a bill that would provide the president with fast-track trade powers, known as trade promotion authority (TPA), that the administration says are needed to finalize international deals it is currently negotiating.

To win the needed votes of moderate Democrats, Republican leaders are promising they will separately move through Congress an extension of a program that provides job training to workers who are hurt by trade deals, so-called trade adjustment assistance (TAA).

“We are committed to ensuring both TPA and TAA get votes in the House and Senate and are sent to the President for signature,” Senate Majority Leader Mitch McConnell (R-Ky.) and Speaker John Boehner (R-Ohio) said in a joint statement.

The White House and congressional Republicans have been scrambling since last week to figure out a way to move the trade bills, a rare area of agreement between the two. On Friday, House Democrats helped derail the fast-track legislation by voting against the worker retraining program because they saw it as a ploy to force them to give tacit support for Obama to negotiate a trade agreement they oppose. The fast-track bill would require Congress to approve trade deals on an up or down vote without amendments.

Obama met Wednesday with pro-trade Democrats in the House and the Senate to sell them on the new plan.

The ultimate success of the new strategy will likely come down to whether pro-trade Democrats, whose votes will be needed in both chambers, believe GOP leaders can move both the TPP and TPA bills to the president’s desk.

Under the plan, the House on Thursday will vote to attach the fast-track legislation to an unrelated bill. If it passes, the legislation would go to the Senate, which would then have to clear the bill. The challenge in the Senate will be to attach the worker retraining program to a package of trade preferences for Africa that also already passed the House. That new bill will then have to pass the House with the support of Democrats.

It is a complicated process that could play out over several days and will require extraordinary trust across party lines and between the two chambers.

The House narrowly passed the fast-track legislation last week on 219-211 vote, but some moderate Democrats could now vote against the proposal if they aren’t confident the workers assistance program will also be approved in the next few days.

“Trust is a very fragile commodity in this town and it is never an absolute,” Rep.  Gerry Connolly (D-Va.) said on Wednesday after a closed door-meeting of pro-trade House Democrats.

Connolly said Boehner assured Democrats that any deal would include a new vote on the worker retraining program and that this time it would pass.

A group of pro-trade Senate Democrats met for about 30-minutes on Wednesday after returning from a meeting with Obama. Most who attended the closed-door session said they would not commit to supporting the new path forward until they see the full package negotiated by Republican leaders and some evidence that the bills can pass the House.

The failure last week has some, like Sen. Ben Cardin (D-Md.), questioning if Boehner can deliver on the commitment. He said the process they tried last week was “cute” but it ultimately failed and he wants to see proof it can work this time.

“Does that mean he has the votes in the Republican caucus for TAA? Bring it up and pass it” Cardin said. “I don’t think he can speak for the Democratic votes, I didn’t know he could speak for the Republican votes.”

The group is expected to keep discussing their approach throughout the evening on Wednesday, according to Sen. Ron Wyden (D-Ore.), the top Democrat on the Senate Finance Committee.

“When I see what the rule actually is we have a chance to have some conversations through the evening with respect to other steps that would show Democratic senators that TPA and TAA are actually going to happen then I’ll have some comments,” Wyden said.