There have always been left leaning politicians and activists that have opposed high immigration levels. Barbara Jordan, Cesar Chavez and A. Philip Randolph are prominent examples. More recently, Peter Defazio has combined membership in the Progressive Caucus with a more restrictive than average voting record on immigration.
Recently, the web page of Progressives for Immigration Reform was brought to by attention. The founders of this organization aren't strangers to VDARE.com readers. Vernon Briggs has a long history of activism in the area of immigration restriction. Frank Morris is a former director of the Congressional Black Caucus Foundation who has become active in Immigration Issues.
From the start, I have believed that effective restriction of immigration will be a bipartisan effort. The real supporters of immigration expansion have been the most wealthy Americans. Part of why I think immigration reform has made so little headway is that groups opposed to high levels of immigration are divided on many other points. For examples, I disagree strongly with Tom Tancredo's idea that restriction of immigration needs to go hand in hand with elimination of income support programs—and removing taxes from the most very wealthy Americans.
I don't think reform of immigration is a left vs. right issue though. The election of figures like George Bush shows that the center of American politics has become incredibly corrupt. I think we need to face a future in which many mainstream political figures are utterly discredited and those of us that remain will have to learn to work with each other.