WRAPUP 7-New Mexico governor backs Obama's W.House bid

(Adds background on Richardson)

By Matthew Bigg

PORTLAND, Ore., March 21 (Reuters) - Sen. Barack Obama won a coveted endorsement from New Mexico Gov. Bill Richardson on Friday while the State Department apologized that employees snooped into the Illinois Democrat's passport files and those of his two main White House rivals.

The backing from the Hispanic governor and former presidential contender is a victory for Obama and could improve his chances of winning over Latino voters who have leaned toward New York Sen. Hillary Clinton.

A Clinton adviser dismissed the endorsement as not significant at this stage in the race.

Obama and Clinton are in a heated battle to represent the Democrats against the presumptive Republican nominee, Sen. John McCain of Arizona, in the Nov. 4 presidential election to succeed U.S. President George W. Bush.

In an embarrassment to the Bush administration, the State Department revealed on Friday that the passport records of all three major candidates had been improperly viewed by three contract employees and by a regular department staffer.

Secretary of State Condoleezza Rice called Obama, Clinton and McCain to apologize and the State Department said it was conducting an investigation and would look at how to tighten its systems to prevent such privacy violations.

"It is deeply disturbing, what's happened," Obama told a news conference.