U.S. Sen. Sam Brownback still hasn’t decided whether to run for president in 2008, but the nickname “Amnesty Sam” might not help his efforts to win the GOP nomination.

That’s the label the Kansas Republican received from the conservative National Review Online after Brownback and three other Republicans joined Democrats on the Judiciary Committee in voting for an immigration bill that offers a pathway to citizenship for some illegal aliens.

“It certainly makes the White House a much more distant prospect for him – more difficult to persuade primary voters, who he’ll have to go to first,” said Mark Krikorian, director of the Center for Immigration Studies, an anti-immigration think tank. Krikorian gave Brownback the “Amnesty Sam” moniker in a blog at National Review.

Human Events, a conservative journal, was even more blunt with a recent online headline: “Brownback Can Kiss ’08 Run Goodbye”

During a conference call with Kansas reporters last week, Brownback said the vote wouldn’t tarnish his conservative credentials with presidential voters.

“It doesn’t affect any decision I have to make in the future,” he said. “I am in a position very similar to Ronald Reagan, the position he took in his time.”

Brownback was referring to a 1986 amnesty under Reagan that experts say allowed 2.5 million illegal aliens to remain, legally, in the United States.

“Ronald Reagan is about as good a conservative light as you can have,” Brownback said. “I don’t have a problem with that.”

And he disputed the label “amnesty” to describe the immigration bill provisions he favors. They would allow illegal immigrants who have been in the United States for more than five years to stay if they registered with the government, learned English, paid taxes and registered with Selective Service while awaiting citizenship.

“Some people call that amnesty,” Brownback said. “I think that looks a lot more like probation.”

Krikorian disagreed.

“The fact is, if the illegal gets to stay, that’s amnesty,” he said.

Brownback also disputed notions that his vote was an attempt to burnish moderate credentials for the electorate, noting that he had taken a similar stance during a 1996 debate on the issue.

“I had a pro-immigration stance then,” he said. “I believe strongly in it.”