Good luck with working with Congress….

U.S. officials said on Tuesday they will work with Congress to find a window for lawmakers to consider a sweeping Pacific trade pact and warned that rejecting the deal would raise questions about America’s leadership in the region.

U.S. Trade Representative Michael Froman said he was confident of winning political support for the Trans-Pacific Partnership (TPP) deal sealed with 11 trading partners earlier this month, which drew a mixed initial response from Capitol Hill.

He said several trading partners had already expressed interest in joining the pact, which will cut trade barriers and set common standards for a region spanning nearly half the world economy.

“It is not a perfect agreement but I think at the end of the day when people dig into the details and learn about what’s in there … I’m confident we will have bipartisan support ultimately for its approval,” Froman said at an Atlantic Council event.

The senior U.S. diplomat for East Asia, Assistant Secretary of State Daniel Russel, said a knock-back by Congress for the deal would cast a cloud over the United States’ leadership in the region.

“It would call into question the possibility that not only in the economic sphere but in the political and security sphere, that American follow-through may be lacking,” he said.

Froman said officials would work with congressional leaders on the timing for introducing legislation to implement the TPP, which some speculate may have to wait until the end of 2016.

“We want to make sure we are taking all the necessary steps to have it ready when a window appears for Congress to take it up,” he said.

Over the last week, South Korea and Indonesia have confirmed their interest in joining and an influential Chinese Communist Party newspaper said on Sunday China should also join at an appropriate time.

The United States has said the pact is open to all who can meet standards on issues ranging from labor rights to intellectual property protections.

But Froman noted China was not there yet, based on progress towards negotiating a bilateral investment treaty.

“When they have raised questions about TPP, we have said let’s … see whether through the negotiation of a bilateral investment treaty, China is ready to take on a high standard agreement and an agreement that would require some substantial reform of their domestic and economic system,” he said.

“We are making good progress on those issues but we still have a ways to go.”