Richardson said he wants to keep a promise to the people of New Mexico to serve a full, four-year term and noted that Kerry has "numerous experienced and talented leaders" from which to choose a vice presidential candidate.
"It is with that knowledge and comfort that I must tell you that I respectfully remove myself from the selection process and withdraw my name from consideration for the vice presidential nomination," Richardson said.
He delivered the news in a letter sent Thursday to Kerry's campaign headquarters.
Kerry campaign spokeswoman Stephanie Cutter declined to comment on the governor's decision.
"Senator Kerry has the utmost respect for Governor Richardson's abilities and leadership both as a leader in New Mexico and across the nation," she said, adding that Kerry looks forward to working with Richardson in the future.
Richardson was one of several politicians mentioned as possible vice presidential candidates for Kerry, who is expected to announce his selection this month, likely ahead of the Democratic National Convention in Boston, which starts July 26.
Other politicians who have been talked about are North Carolina Sen. John Edwards (search), Missouri Rep. Dick Gephardt, Florida Sen. Bob Graham and Iowa Gov. Tom Vilsack, among others.
In the letter, Richardson spoke of the commitment he made to the people of New Mexico after taking office in January 2003, issues his administration has dealt with and the work that he says remains to be done.
"I need to honor that pledge," he wrote.
Richardson, who had said on several occasions that he was very happy learning the ropes as governor, apparently reached his decision after a two-hour meeting with Kerry on Tuesday in Phoenix, a person familiar with the process said Thursday. Kerry was in Arizona to address a meeting of the National Council of La Raza (search), a Hispanic civil rights group.
Although his name was often mentioned — largely because of his Hispanic heritage — Richardson was not considered a leading candidate for the No. 2 slot. And adding him to the ticket would not have risk-free for Kerry.
Soaring oil prices, security problems at Los Alamos National Laboratory (search) in New Mexico and the government's flawed investigation and prosecution of former nuclear weapons scientist Wen Ho Lee marked Richardson's two years as energy secretary during the Clinton administration.
He later said both problems likely diminished his changes to be Democrat Al Gore's running mate in 2000.
Richardson, 56, is a former congressman who represented New Mexico in the House from 1982 to 1997. President Clinton appointed him U.S. ambassador to the United Nations in 1997, and a year later put him in charge of the Energy Department.