By RUSH LIMBAUGH

I understand the rough and tumble of politics. But Barack Obama -- the supposedly postpartisan, postracial candidate of hope and change -- has gone where few modern candidates have gone before.

Mr. Obama's campaign is now trafficking in prejudice of its own making. And in doing so, it is playing with political dynamite. What kind of potential president would let his campaign knowingly extract two incomplete, out-of-context lines from two radio parodies and build a framework of hate around them in order to exploit racial tensions? The segregationists of the 1950s and 1960s were famous for such vile fear-mongering.

Here's the relevant part of the Spanish-language television commercial Mr. Obama is running in Hispanic communities:

"They want us to forget the insults we've put up with . . . the intolerance . . . they made us feel marginalized in this country we love so much."

Then the commercial flashes two quotes from me: ". . . stupid and unskilled Mexicans" and "You shut your mouth or you get out!"

And then a voice says, "John McCain and his Republican friends have two faces. One that says lies just to get our vote . . . and another, even worse, that continues the policies of George Bush that put special interests ahead of working families. John McCain . . . more of the same old Republican tricks."

Much of the media that is uninterested in Mr. Obama's connections to unrepentant 1970s Weather Underground terrorist William Ayers and Rev. Jeremiah Wright have so far gone along with the attempt to tie me to Mr. McCain. But Mr. McCain and I have not agreed on how to address illegal immigration. While I am heartened by his willingness to start by securing the borders, it is no secret that we have fundamental differences on illegal immigration.

And more to the point, these sound bites are a deception, and Mr. Obama knows it. The first sound bite was extracted from a 1993 humorous monologue poking fun at the arguments against the North American Free Trade Agreement. Here's the context:

"If you are unskilled and uneducated, your job is going south. Skilled workers, educated people are going to do fine 'cause those are the kinds of jobs Nafta is going to create. If we are going to start rewarding no skills and stupid people, I'm serious, let the unskilled jobs that take absolutely no knowledge whatsoever to do -- let stupid and unskilled Mexicans do that work."

My point, which is obvious, was that the people who were criticizing Nafta were demeaning workers, particularly low-skilled workers. I was criticizing the mind-set of the protectionists who opposed the treaty. There was no racial connotation to it and no one thought there was at the time. I was demeaning the arguments of the opponents.

As for the second sound bite, I was mocking the Mexican government's double standard -- i.e., urging open borders in this country while imposing draconian immigration requirements within its own borders. Thus, I took the restrictions Mexico imposes on immigrants and appropriated them as my own suggestions for a new immigration law.

Here's the context for that sound bite: "And another thing: You don't have the right to protest. You're allowed no demonstrations, no foreign flag waving, no political organizing, no bad-mouthing our president or his policies. You're a foreigner: shut your mouth or get out! And if you come here illegally, you're going to jail."

At the time, I made abundantly clear that this was a parody on the Mexican government's hypocrisy and nobody took it otherwise.

The malignant aspect of this is that Mr. Obama and his advisers know exactly what they are doing. They had to listen to both monologues or read the transcripts. They then had to pick the particular excerpts they used in order to create a commercial of distortions. Their hoped-for result is to inflame racial tensions. In doing this, Mr. Obama and his advisers have demonstrated a pernicious contempt for American society.

We've made much racial progress in this country. Any candidate who employs the tactics of the old segregationists is unworthy of the presidency.

Mr. Limbaugh is a nationally syndicated radio talk-show host.