New Florida Sen. George LeMieux's first foray into foreign relations has drawn brickbats from former high-ranking State Department officials who say his effort to block the Obama administration's new ambassador to Brazil is damaging U.S. relations with Latin America.

"This continuing, prolonged vacancy sends an unintended signal that the United States does not consider Brazil an important relationship,'' the nine former assistant secretaries of state wrote in a letter to LeMieux, urging him to lift his opposition to nominee Tom Shannon.

Shannon had triggered the ire of South Florida Cuban Americans who believed he wasn't tough enough on the Castro regime during his tenure as a former assistant secretary of state for Western Hemisphere affairs under President George W. Bush.

Senate staffers suggested Wednesday that LeMieux -- who was appointed by Gov. Charlie Crist to fill the seat vacated by Mel Martinez -- could be trying to burnish his Cuba credentials to help Crist, who faces a Cuban-American opponent in the Republican primary for the Senate seat.

LeMieux said it was his responsibility as Florida's senator to vet the nominee, noting that he had heard concerns about Shannon's record from constituents and fellow members of Congress.

"I feel like I have a role and a responsibility far greater than other senators do in terms of anything that deals with Latin America, and I take that job seriously,'' said LeMieux, who will be a "special guest" at a DC fundraiser Friday for Crist. "This is about the entire hemisphere. This is about Venezuela, El Salvador, Bolivia, Colombia and Brazil and Cuba and the role that Mr. Shannon played . . . and the role he will play. We are burning the midnight oil here to make sure I'm doing the best job I can for 18 million Floridians, and that's my motivation.''

Bloomberg News reports the extended hold could cost Boeing Inc. up to $7.5 billion.