The United States and Peru signed a free trade agreement on Wednesday, setting the stage for a potentially tough fight in Congress unless the Bush administration offers Democrats stronger assurances that Lima will abide by international labor standards, Reuters reported. "This agreement with Peru is instrumental in our strategy to advance prosperity within our hemisphere," U.S. Trade Representative Rob Portman said in a statement. "We look forward to continuing to build bipartisan support for the U.S. - Peru Trade Promotion Agreement in both houses of Congress in order to quickly approve this high-quality pact." However, the agreement faces an uncertain future in Peru, where leading presidential candidate Ollanta Humala has said the pact must be scrapped or renegotiated. Humala, a nationalist, won the first round of the presidential election on Sunday with around 31 percent of the vote. Leftist former president Alan Garcia, who also opposes the free trade agreement, is in a close race for second place with Lourdes Flores, a lawyer and former congresswoman who is the choice of international investors. A runoff between Humala and the candidate eventually declared the second place finisher is expected by early June. Peru's current President Alejandro Toledo joined Peruvian Trade Minister Alfredo Ferrero at the signing ceremony on Wednesday. Toledo sees the free trade pact as his political legacy and wants to convince Peru's Congress to approve it before he leaves office on July 28. The pact is similar to an agreement the U.S. Congress narrowly approved last year with five Central America countries and the Dominican Republic. Many Democrats who complained that pact's labor provisions were not strong enough are making the same argument again with Peru. --more 23 22 Local Time 20 22 GMT