WASHINGTON (Yonhap News) -- Republican U.S. senators on Thursday boycotted a crucial session to discuss free trade pacts with South Korea, Colombia and Panama, dealing a setback to President Barack Obama's strong push to get the long-pending deals ratified before early August.

On Tuesday, the White House announced a breakthrough in efforts to move forward the free trade agreements (FTAs) with the nations, saying it struck an agreement with the House of Representatives on the Trade Adjustment Assistance (TAA) program intended to fund re-training and health care for displaced workers.

Senate Finance Committee Chairman Max Baucus (D-Mont.) convened a "mock markup," which gives senators a chance to request amendments to the bill.

But Republican members of the committee did not show up for the session in protest of Obama's plan to tie the TAA to the FTA with South Korea, dubbed KORUS FTA. Republicans, who question the effectiveness of the budget-gulping TAA, wants to separate the issue from the pact's ratification.

Democratic senators claimed their Republican colleagues were trying to use the economic issue for political gain ahead of next year's presidential elections.

"I was dumbfounded by what has happened here today," John Kerry

(D-MA) said, pointing at empty seats on the other side of the aisle.

The mock markup hearing is aimed to send non-binding amendments to the White House under the "fast-track" trade promotion authority and the president will send a final bill to Capitol Hill for just a "yes or no" vote.

The Obama administration wants Congress to ratify the FTAs before it goes into summer recess on Aug. 5.