Part of the reason, government documents and other evidence suggest, is that he tried to protect voting rights for Native Americans.

At a time when GOP activists wanted U.S. attorneys to concentrate on pursuing voter fraud cases, Heffelfinger’s office was expressing deep concern about the effect of a state directive that could have the effect of discouraging Indians in Minnesota from casting ballots.

Citing requirements in a new state election law, Republican Secretary of State Mary Kiffmeyer directed that tribal ID cards could not be used for voter identification by Native Americans living off reservations. Heffelfinger and his staff feared that the ruling could result in discrimination against Indian voters. Many do not have driver’s licenses or forms of identification other than the tribes’ photo IDs.

Kiffmeyer said she was only following the law.

The issue was politically sensitive because the Indian vote can be pivotal in close elections in Minnesota. The Minneapolis-St. Paul area has one of the largest urban Native American populations in the United States. Its members turn out in relatively large numbers and are predominantly Democratic.

Heffelfinger resigned last year for personal reasons and says he had no idea he was being targeted for possible firing. But his stance fits a pattern that has emerged in the cases of several U.S. attorneys fired last year in states where Republicans wanted more vigorous efforts to legally challenge questionable voters.

Politics have always played a role at Justice and other Cabinet-level departments. But, critics say, Bush administration strategists went beyond most of their predecessors — Democratic or Republican — in seeking ways to convert control of the federal government into advantages on election day.

And the Heffelfinger episode has contributed to a backlash among some Minnesota Republicans. Sen. Norm Coleman, a Bush loyalist in the past who is facing reelection next year, has called on Atty. Gen. Alberto R. Gonzales to resign — largely as a result of the U.S. attorney firings and the revelations about Heffelfinger.

A hint at why Heffelfinger’s name was on termination lists that Justice Department officials and Bush political strategists put together emerged when Monica M. Goodling, the department’s former White House liaison, testified last week before the House Judiciary Committee about the firings.

Goodling said she had heard Heffelfinger criticized for "spending an excessive amount of time" on Native American issues.

Her comment caused bewilderment and anger among the former U.S. attorney’s supporters in Minnesota. And Heffelfinger said it was "shameful" if the time he spent on the problems of Native Americans had landed him in trouble with his superiors in Washington.

But newly obtained documents and interviews with government officials suggest that what displeased some of his superiors and GOP politicians was narrower and more politically charged — his actions on Indian voting.

About three months after Heffelfinger’s office raised the issue of tribal ID cards and nonreservation Indians in an October 2004 memo, his name appeared on a list of U.S. attorneys singled out for possible firing.

Justice Department officials refused Tuesday to confirm whether particular U.S. attorneys may or may not have been on one of the termination lists prepared by D. Kyle Sampson, the former chief of staff to Gonzales.

Boyd cited cases in which Justice Department lawyers have gone to court to uphold Indian voting rights.

Suspicion of Indian voter fraud was strong among Republicans in the upper Midwest in advance of the 2004 election. The GOP blamed what it said was fraud on Indian reservations for the narrow victory of South Dakota Democratic Sen. Tim Johnson over Republican candidate John Thune in 2002.

It was in this environment, Rich says, that he got an Oct. 19, 2004, e-mail from an assistant U.S. attorney in Minnesota named Rob Lewis, informing him about possible voter discrimination against Indians.