By Doug Palmer

WASHINGTON (Reuters) - A Senate panel on Tuesday backed long-delayed trade pacts with South Korea, Colombia and Panama that are expected to boost U.S. exports by about $13 billion a year, paving the way for final approval.

The full Senate and House of Representatives are poised to approve the agreements on Wednesday, just nine days after President Barack Obama sent them to Congress. Obama has said they would help support tens of thousands American jobs.

The panel approved the South Korea and Panama agreements on voice votes and the Colombia pact by a 18-6 vote.

U.S. farm and manufactured goods exports are expected to rise under all three agreements as tariffs are phased out, with the biggest gains coming from the South Korea agreement. The deals also open new markets for U.S. companies in service sectors such as banking, insurance and express delivery.

The deals "will give our ranchers, farmers, workers and businesses a competitive edge in three lucrative fast-growing markets," Senate Finance Committee Chairman Max Baucus said.

The speed at which the deals have moved through Congress contrasts with the four to five years they were stuck at the White House because of mostly Democratic Party concerns.

Senator Orrin Hatch, the top Republican on the panel, said the long period of inaction had "weakened" U.S. leadership in global trade and "led many to doubt whether the United States remains serious about addressing the world's and its own economic challenges."

House Democratic Whip Steny Hoyer told reporters on Tuesday he expected all three agreements to pass with bipartisan support. Opponents say they expect more than half of House Democrats to go against Obama and oppose the deals.

Senate Republican Leader Mitch McConnell also said he expected approval of all three pacts, which would come just a day before South Korean President Lee Myung-bak speaks to a joint session of the Congress.

(Additional reporting by Thomas Ferraro; Editing by Bill Trott and Paul Simao)