* Republican Bunning in new showdown with Democrats
* Job "too important" to go unfilled, senator says
* Delay has fueled criticism of U.S. at WTO
By Doug Palmer
WASHINGTON, March 10 (Reuters) - A Republican senator who held up action earlier this month on a bill to renew jobless benefits faced more criticism on Wednesday for blocking approval of President Barack Obama's nominee to be U.S. ambassador to the World Trade Organization.
Senator Jim Bunning, a Kentucky Republican, has delayed the Senate from approving Michael Punke to be ambassador to the WTO in Geneva. This has fueled criticism that the United States is not fully engaged in the Doha round of world trade talks, which have already dragged on for eight years.
"This job is too important to remain open because one senator has a flimsy policy beef," said Senator Jon Tester, a Democrat from Montana, complaining on the Senate floor about Bunning.
"Our trading partners use his absence as an excuse to stall progress on serious negotiations," said Tester, whose frustration with the delayed nomination is shared by the Obama administration.
Both Punke and Isi Siddiqui, Obama's choice to be chief U.S. agricultural trade negotiator, won unanimous backing from the Senate Finance Committee in December.
MOVED TIED TO CANADA SMOKING LAW
But Bunning, who is a member of the Finance Committee, has used his right under Senate rules to block further action on both nominations. He is stalling in an effort to put pressure on the Obama administration to prod Canada to change parts of its anti-smoking legislation.
"To fully represent the interests of the United States in trade negotiations we need everybody on our team at the table," Nefeterius McPherson, a spokeswoman for the U.S. Trade Representative's office said.
"A year into this administration, USTR and the president deserve to have these nominees in place," she said.
Bunning delayed Senate action for about a week on a bill to fund jobless benefits, highway construction and other government programs until his fellow Republicans worked out a deal to allow the legislation to move.
The tobacco-state senator, before he turned his attention to Punke and Siddiqui, previously blocked a Senate vote on Miriam Sapiro to be deputy U.S. trade representative.
His colleagues sidestepped Bunning and approved Sapiro along with a long list of other nominees on Dec. 24, when the Kentucky senator was absent for votes.
Bunning then placed a hold on Siddiqui and Punke.
"The reason Senator Bunning gives for his hold? He wants Canada to repeal parts of the anti-smoking law that they passed in the Canadian parliament. I don't think that holds water," Tester said.
There was no immediate response from Bunning's office to Tester's speech.
WTO Director General Pascal Lamy was in Washington on Wednesday for talks with U.S. Trade Representative Ron Kirk and other top U.S. officials.
His visit came one day before Obama will give a speech on the importance of boosting U.S. exports to create jobs.
(Reporting by Doug Palmer; Editing by Cynthia Osterman)