Immigration failed to become an issue in the 2004 election, he says, "because both major parties agreed that they would do nothing to defend the borders and that we ought to have amnesty for those who break in illegally. There was no choice."
Although he supported Mr. Bush's re-election, he says the president "has abdicated his responsibility to defend America from a foreign invasion. We add half a million illegals to our population each year, most of whom come to work, some to commit crimes against American citizens."
A desire to secure the nation's borders against an immigrant invasion has nothing to do with the "nativism" that critics ascribe to him, he says.
"I say, look, the kind of immigrants we want are people who want to come here and become part of the American family ... not just to work and then go back home."
He warns of long-term consequences.
"Look, you're going to have 100 million people of Hispanic, primarily Mexican, descent in the American Southwest by the middle of this century, and I think you are in danger of losing the American Southwest, de facto. I think this country is risking coming apart, like other countries in the world, over issues of language, culture and ethnicity."
Opposition to Mr. Bush's proposed guest-worker program, which would allow illegal aliens to gain legal residency here, may herald a conservative comeback, Mr. Buchanan says.
"The president is in trouble," he explains. "He's on the defensive, because he is not going to get his guest-workers program. He's going to get a House that tries to impose upon him the obligation to do his duty and defend this country from the invasion from Mexico, which he has refused to do."