The naming of a new Navy cargo ship after farm labor leader Cesar Chavez continues to rankle conservatives in Congress who want to tighten controls over the ship naming tradition.

The angst over the Chavez decision boiled over earlier this month when the same lawmakers demanded that a review of how military ships are named be conducted.

A clause in the Dec. 12 congressional report accompanying the defense authorization bill calls on the defense secretary to review the policy for naming vessels, which has been a centuries-old prerogative of the Navy secretary.

For critics, Exhibit A is the USNS Cesar Chavez, a dry cargo and ammunition ship under construction in San Diego.

"The Obama administration seems to be politicizing the ship-naming process," said Joe Kasper, spokesman for U.S. Rep. Duncan Hunter, R-San Diego. Hunter is been an outspoken critic of the Chavez decision.

U.S. Rep. Sam Farr, D-Carmel, disagrees. He said the decision to name the Chavez ship was a good one that he fully supports.

"For 200 years the Navy has held a long and proud tradition of naming ships after figures that have played important roles in our nation’s history. The names of these historic Americans have traveled the world on the side of our ships, representing our country’s core values of freedom, liberty and equality. Naming a ship after Cesar Chavez continues that tradition and embodies these core values," Farr said.

Proponents agree that the name is appropriate because Chavez, who organized farm workers into a union with a membership at its peak of 50,000 strong, served in the Navy, and the Lewis and Clark-class cargo ships are named after such pioneers.

Examples include astronaut Alan Shepard, explorer Robert Peary, physician Charles Drew and Sacagawea, a Native American who guided Meriwether Lewis and William Clark on their transcontinental expedition from 1804 to 1806.

A clause in the defense authorization bill, introduced by Sen. Roy Blunt, R-Mo., calls for a sweeping review of the Navy’s vessel-naming practices, including whether it conforms to historical standards.

The clause also calls for a description of naming conventions and whether it is feasible for the Navy to establish fixed naming policies for a class of ships. A report is to be provided to Congress within six months of the authorization bill passing. A spokeswoman for Navy Secretary Ray Mabus defended the recent ship names.

"While there have always been exceptions to naming conventions for ship classes, generally speaking, names are chosen to honor individuals who have displayed uncommon commitment, service or courage, or to recognize geographic locations or traits that represent American values," Navy Capt. Pamela Kunze said.

The 200-year-old practice, she said, "allows the secretary of the Navy to consider ship-naming nominations he receives through a variety of sources, including the American public, members of Congress, industry and the chain of command."

Marc Grossman, a spokesman for the Keene-based Cesar E. Chavez Foundation and a longtime personal aide and speech writer for the late labor leader, said the foundation is disappointed over the acrimony caused by the conservative-led naming kerfuffle.

"The naming of this ship honors not just him but all Latinos who have built and defended this country," Grossman said in a brief interview. "That’s why Cesar’s family is very proud that this fine vessel will bear his name."

To be sure, in the exalted realm of ship naming, exceptions abound. Virginia-class attack submarines are named for states, except for the sub named after former U.S. Senator John Warner. Aircraft carriers are named for presidents, except for the Enterprise, along with the three named for a congressman, senator and fleet admiral.

Controversy and political maneuvering are nothing new to ship naming, according to one former Navy official.

"It has been politicized since 1776," said A.D. Baker III, who submitted name recommendations while working for Navy Secretary John Lehman in the 1980s. "It has always been politicized. The only time it wasn’t politicized was during World War II, when they had to name so many ships, so quickly."

The 689-foot Chavez, due to be launched May 5, is a unique cargo carrier designed to conduct underway replenishment of other Navy combat vessels.

Underway replenishment involves a ship like the Chavez carefully maneuvering alongside another large vessel — typically an aircraft carrier or destroyer — and transferring cargo and fuel, all the while moving through the water at or near full speed. The goal of the operation is to not stop or slow the combat ship as it takes on needed supplies, Navy officials say.

Those same officials say the Chavez — once it is fitted out, goes through sea trials and is finally delivered to the U.S. Military Sealift Command sometime next fall — will be part of a squadron of cargo ships that will be "prepositioned" near military hotspots around the world.