* Republican Grassley says U.S. risks being left behind
* Senator says political concerns hindering trade deals
WASHINGTON, June 18 (Reuters) - The United States risks being "wallflowers at the dance" as other countries pursue trade deals while the Obama administration sits on the sidelines, a senior Republican senator said on Thursday.
The Democratic Obama administration so far has only produced false starts on trade, allowing itself to be sidetracked by congressional Democrats and unionists who oppose some trade deals, Senator Charles Grassley said.
He said he feared the White House would not submit a free trade agreement with Panama to the Democratic-controlled Congress for approval before next year and doubted another pact negotiated with Colombia would come up even then.
Grassley, the senior Republican on the Senate Finance Committee, sensed no White House plan for submitting to lawmakers a trade deal that the United States negotiated with South Korea. All three pacts were negotiated by the Bush administration but must be ratified by Congress to go into effect.
"We are in need of real leadership to make sure that the United States remains at the economic forefront for the coming decades, but the president and his advisers are sidetracked by political considerations," Grassley told a trade association breakfast in Washington.
"All we've seen is false starts from the administration, and even more backsliding from the majority party, particularly in the House," he said.
Obama administration officials have sent conflicting signals on trade this year. Initially, they said they were working hard on readying the Panama deal for Congress.
Then they indicated last month that the Panama deal would wait until Obama outlined a new trade policy framework, and said this framework needed to be in sync with domestic policy.
Meanwhile some 50 House of Representatives Democrats have demanded that the Panama deal be renegotiated, saying they are concerned about Panama's tax and labor laws.
Grassley warned that U.S. exports had fallen this year as officials dithered over trade pacts. Meanwhile Canada was conducting trade negotiations with Panama and had already completed talks with Colombia, he said. The European Union was also negotiating with Colombia and South Korea, he said.
"We've in a sense been wallflowers at this dance before," Grassley said. Between 1995 and 2002, U.S. negotiating partners concluded over a hundred trade deals while the United States clinched just three, he said.
(Editing by Eric Beech)