But a primary election next week has changed that: Shirley is running for re-election, and Dayish is seeking to oust him. They are among 11 candidates for president.

Their campaign trailers sit less than a half-mile apart, but that's about as close as they get these days. They keep separate schedules and rarely talk to each other.

''They never travel together, and if by chance we happen to show up at the same meeting, it's coincidental,'' Maxine Etter, a spokeswoman for Dayish, recently told The Associated Press.

''You would think that there would be continuous communication, but it just isn't working that way right now,'' said George Hardeen, Shirley's spokesman.

Shirley, 59, and Dayish, 47, have refused to discuss the split between them and have not publicly been critical of one another.

As the incumbent and sitting vice president, the two are widely recognized on the reservation and, election observers say, among the front-runners to win the Aug. 8 primary and face each other in November.

Navajo officials have discussed the tribe's first casino, which Dayish and Shirley both support. The tribe also plans to build a 1,500-megawatt coal-fired power plant that could be operating by 2010 - another controversial project that both men praise. In fact, both men tout economic development as crucial and appear to have few, if any, policy differences.

But the fact that Dayish, a soft-spoken former Marine with a background in the aerospace and mining business, did not step down from office after announcing a run for the presidency has irked Shirley.

Shirley, a former Apache County supervisor and Navajo council delegate, said it was disrespectful of Dayish to run while serving as vice president.

Dayish is making his first run at the presidency and said Shirley did not tell him about his intent to seek re-election.