George Marlin, a longtime conservative activist in New York, has a problem with Mayor Giuliani. In 1993, Mr. Marlin ran for mayor on the Conservative line against Mr. Giuliani and David Dinkins — once bringing a rubber chicken to a debate where Mr. Giuliani didn’t show up. Now, he’s put together a 40-page dossier, reproduced here, of every “liberal” quote he could find from or about the former mayor, and he’s begun mailing it to conservative activists nationwide.

Recently, Mr. Marlin spoke to The New York Sun about his dossier, why his quarrel with Mr. Giuliani is so heated, and why Fred Thompson should be the Republican nominee for president.

NYSun: What is your motivation for launching such an aggressive attack against the former mayor, Rudy Giuliani?

George Marlin: I think it’s time that conservatives, particularly on a national level, begin to understand what Rudy Giuliani has stood for throughout his entire life. From his college days to the present, in my judgment, he’s a liberal. And now to put a spin that he is Mr. Conservative, on life issues, on gun issues, or wherever else he’s changing his tune this week, I think it’s wrong. And I, in good conscience, cannot support Rudy Giuliani for president. I, in good conscience, cannot support a pro-abortion candidate for president of the United States. And I think when people down South, in the Southwest, and in the West begin to see what the real Rudy Giuliani record is, they may change their tune a little. Polls show most people don’t know where he stands on the issues.

NYS: So, you would sit out the 2008 election if he were the nominee? Would you support a third-party candidate?

Marlin: I would sit out the election. I can’t see any alternatives. If the unintended consequence is the election of Hillary Clinton, that is just that. I, in good conscience, cannot support a pro-abortion candidate for president of the United States.

NYS: Is this a case where the people who know Mr. Giuliani best like him least?

Marlin: I think that there’s some accuracy to that statement. The media tells me that all the stuff I put in here is old news. Well, that was the Rudy spin for a while. It’s new to a lot of people around this nation. I know this has been e-mailed to tens of thousands of people. People are taking an interest in it, the message is getting around, and we’ll see how it plays.

NYS: To whom are you mailing this?

Marlin: It is going to all of the local and national conservative organizations throughout this country — conservative organizations and religious organizations.

NYS: Do you think Mr. Giuliani has migrated at all to the right, even if it’s not as far right as you might like?

Marlin: No, I don’t buy that at all. I think that’s the great fraud. He’s been a liberal his entire life. There are a lot of reasons to oppose George Pataki for governor [as Mr. Giuliani did in 1994]. The reasons he gave were that Pataki cut taxes and that he had a right-wing voting record. Rudy’s been a lifelong liberal. For us to take a few crumbs from Rudy Giuliani on a few issues, I just don’t buy it.

He has been anti-gun going back to the Reagan administration. His fiscal management — yeah, his first term was okay by my standards, but then again so was Pataki’s. Once the money was there, Rudy was a drunken sailor just like Pataki was a drunken sailor. He’s not a fiscal conservative by nature. He’s not a conservative philosophically by nature. Never has been.

So, why should we take a few crumbs as the Republican Party from Rudy Giuliani. Why should we buy it? I’d rather support Fred Thompson for president, for goodness sake, personally. I hope Fred Thompson jumps in here. He may be the guy who saves the day for the Republican Party in my judgment.

I have discovered that when you have guys who suddenly try to play both sides against the middle, they end up annoying both sides. I think we’ll see the self-destruction of Rudy Giuliani. … I’m not overwhelmed with anybody at the moment. I could probably live with John McCain.

NYS: What do you like about Mr. Thompson?

Marlin: First of all, I think he’s a very solid guy. He has some pizzazz. He’s pretty good. I don’t know if he’s going to do it. The guy sounds pretty good to me.

For the Republican Party to nominate a pro-abortion Republican like Rudy Giuliani, I don’t think the party has yet grasped that a lot of people like George Marlin are just going to sit on their hands. If Catholic voters sit on their hands, states like Ohio and Missouri are just going to go Democratic. These voters matter in tight elections.

NYS: The Giuliani camp would probably say they could make up the votes in the center.

Marlin: I don’t buy that. If you look at last fall’s elections, the big people who went down were the socially liberal Republicans. Most of those so-called moderates went down. You cannot out-left the Democratic Party. Your base vote deserts you.

NYS: What about George Will’s praise of Mr. Giuliani, calling his eight years as mayor a great success for conservative governance? Don’t Mr. Giuliani’s results in New York City matter?

Marlin: George Will also was touting Bill Weld for governor of New York. What plays in New York doesn’t play on a national level. George Will can toot this horn from now to kingdom come and think he’s the great pragmatist, but I don’t think it’s going to fly nationally.

NYS: But what about the concrete results on crime and welfare?

Marlin: I don’t buy it. Being mayor is not the same as being president. There are greater issues that concern me. He wasn’t the guy then, he’s not the guy now.

Mr. Sager is the online editor of The New York Sun.