While Mayor Bloomberg was setting the stage for an independent presidential run, Mayor Giuliani was swerving off course on the question of immigration. As mayor himself, Mr. Giuliani was an articulate advocate for immigration. In remarks at Ellis Island on June 10, 1997, he said, “Ellis Island may now be a museum, but if you go to Kennedy Airport you’ll see new immigrants who share the same emotions as the immigrants who came through Ellis Island.”

“Dynamic immigrant communities are a tremendous resource for growth.… Immigrants constantly infuse new life into our economy and culture,” Mr. Giuliani said at the time. He criticized what he called “anti-immigrant legislation” passed by the Republican Congress. “The philosophical underpinnings of this legislation seems to be an attempt to make America an unattractive place for new people. I believe that kind of thinking undermines the character of our nation,” Mr. Giuliani said then.

“Almost all of the last several years has been spent talking about the negative impact of immigration,” Mr. Giuliani said. “It’s the age old conflict in America between pessimism and optimism. Do you see people as problems or as opportunities? . . . The new people that come here not only make a better life for themselves but for us all.”

Mr. Giuliani had it right back in 1997, but now his campaign is circulating an oped by longtime anti-immigrant activists such as Rep. David Dreier of California headlined, “Giuliani’s The Man to Secure Our Borders.” Now no. 2 of Mr. Giuliani’s “12 Commitments” is “I will end illegal immigration, secure our borders, and identify every non-citizen in our nation.” Nothing there about how immigrants “infuse new life into our economy and culture.” Worse, the second commitment follows immediately after language about keeping American on offense in the war on terrorism, suggesting that Mr. Giuliani now sees immigration primarily as a counter-terrorism issue, i.e., a problem, rather than an economic growth issue, i.e., an opportunity.

This is an important moment for the GOP, where leadership on this issue now lies with Senator McCain, who has been doggedly working in Washington with both President Bush and Senator Kennedy on a compromise that would increase the number of legal immigrants. It’s not a perfect bill, but neither are the current unrealistically low immigration limits perfect. Better to repair it than to give up on increasing immigration levels and bringing illegal immigrants out of the shadows. Failure by the GOP on this issue — to explain that we cannot win with protectionist, anti-growth measures — will leave the party exposed to the attack by Mr. Bloomberg that we sketch above.