WASHINGTON- Nearly 700 members of the United Steelworkers union came to Capitol Hill this week to lobby against the Trans-Pacific Partnership trade deal, saying the proposal is hurting American jobs.

The TPP is an agreement that involves 12 Pacific border countries: Japan, Malaysia, Vietnam, Singapore, Brunei, Australia, New Zealand, Canada, Mexico, Chile, Peru and the United States. The pact aims to deepen economic ties between these nations, in part, by lowering trade barriers. The agreement has been the subject of eight years of negotiations, and Congress still needs to to ratify it.

But critics have said that the TPP would create unfair advantages for foreign manufacturers that use cheap labor.

“They say that American worker is too expensive to compete on that global level,” said Vonie Long, a fourth-generation steel worker from Reading, Pennsylvania.

In the last 20 years, U.S. steel and aluminum industries have suffered significant job losses and plant closures. Although the Obama administration’s goal is to increase Made-in-America exports and grow the American economy, manufacturing workers are concerned that the trade deal could threaten their jobs.

“China dumping steels on our shores” has cost the U.S. potentially thousands of jobs, said Candy Sprague, who was recently laid off by United Taconite, an idled iron ore pellet producing plant in Forbes, Minnesota. “And, we are not working because Americans are buying the foreign steel.”

The union members went from door to door in the U.S. House and Senate, telling lawmakers to reject the TPP trade agreement. Many senators and Congress members expressed their opposition to the deal.

“After this election, after Hillary wins this election in November, TPP is gonna be done with,” said Sen. Sherrod Brown, D-Ohio.

All of the leading candidates for President, including Hillary Clinton, Donald Trump and Ted Cruz, have expressed some opposition to the trade bill.

“When I’m president, guess what? Steel is coming back to Pittsburgh!” said Trump at a rally in Pittsburgh on April 13.

Trump predicted that if the “horrible deal” passes, it will allow China “to come in, as they always do, through the back door and totally take advantage of everyone.”

China is not a part of the TPP.

Union leaders say United Steelworkers is waiting for the end of the primary campaign before endorsing a candidate – most likely Clinton or Democratic rival Sen. Bernie Sanders, D-Vermont.

In February, House Speaker Paul Ryan, R-Wisconsin, told reporters that the trade deal doesn’t have enough votes to pass Congress right now.