Rand Paul is walking back his much-derided comments about the 1964 Civil Rights Act, saying he's been "trashed up and down" by Democrats eager to sink his bid for Kentucky's open seat in the U.S. Senate. (Watch Rand Paul defend himself on ABC News.) For their part, liberals have argued that Paul's libertarian ideology lies well outside the mainstream of American politics. "I take Paul at his word that he's not a racist," says Ezra Klein at The Washington Post. "What he is, however, is an ideological extremist." Is that the case? Here is a look at some of Paul's most controversial beliefs, in his own words:

1. Government shouldn't require private businesses to serve customers of all races
"I don’t like the idea of telling private business owners — I abhor racism. I think it’s a bad business decision to exclude anybody from your restaurant — but, at the same time, I do believe in private ownership."
Interview with Louisville Courier-Journal, April 25, 2010

2. The U.S. is secretly planning a European Union-style merger with Mexico and Canada
"I saw the YouTube of [former Mexican president] Vincente Fox talking about [the single North American currency] the Amero. So, it's not a secret. Now it may not be [here] tomorrow, but it took 'em 20 or 30 years to get the Euro, and they had to push people kicking and screaming.... But I guarantee you it's one of their long term goals to have one sort of borderless, mass continent."
Ron Paul campaign event, Bozeman, MT, 2008

3. A nuclear Iran isn't necessarily a threat
"Our national security is not threatened by Iran having one nuclear weapon." 
Ron Paul rally, Burlington, VT, October 2007

4. Rein in Medicare — but not Medicare's payments to doctors (presumably including Rand Paul, a practicing optometrist who says half his patients are on Medicare)
"Medicare is socialized medicine," and one way to control medical costs would be to impose a $2,000 deductible in the program. "But try selling that one in an election."
Comments in Lexington, KY, June 2009

5. Mountaintop coal mining is good for real estate values
"I think whoever owns the property can do with the property as they wish, and if the coal company buys it from a private property owner and they want to do it, fine. The other thing is that I think coal gets a bad name, because apparently a lot of the land is desirable once it gets flattened out... I don’t think anyone’s going to be missing a hill or two here and there. Some people like the flat land, and some of it apparently has become rather valuable when it’s become flattened."
TV interview, October 2009