Immigrants — both legal and illegal — have accounted for all of the job gains in the U.S. labor market since 2000, according to a report that highlights the stiff competition for jobs in a tight economy as Congress debates adding more workers to the mix

The Center for Immigration Studies report says that 22.4 million immigrants of working age held jobs at the beginning of 2013, up 5.3 million over the total in 2000. But native-born workers with jobs dropped 1.3 million over that same period, from 114.8 million to 113.5 million. Meanwhile, the number of Americans who aren’t in the labor force at all has jumped by almost 13 million to reach 48.6 million — a finding that the report’s authors say signals profound changes in the American job market and challenges conventional wisdom that immigration is good for the economy. “The last 13 years, or even the last five years, make clear that large-scale immigration can go hand-in-hand with weak job growth and declining rates of work among the native-born,” the authors, Steven A. Camarota and Karen Zeigler, say in their report. “Given the employment situation in the country, the dramatic increases in legal immigration contemplated by the Gang of Eight immigration bill seem out of touch with the realities of the U.S. labor market.” Whether immigrants compete for jobs is a heated topic — though the Senate all but ignored it during the chamber’s debate on its bill to legalize most illegal immigrants and create opportunities for new immigrants and temporary workers to enter the United States. The outlines of those programs are coming into view. The Congressional Budget Office calculated that boosts in immigration and guest-worker programs would add about 12 million new people to the United States in 2023, in addition to millions of illegal immigrants who would gain legal status and work permits.