The Center for American Progress, which describes itself as a progressive, nonpartisan educational institute, says on its website about the Senate’s immigration legislation S.744, “Moreover, given that the CBO determined that unemployment would not rise as immigration reform increased the labor force, this significant economic growth would create millions of new jobs all across the country.” (http://www.americanprogress.org/issues/immigration/news/2013/06/21/67514/the-6-key-takeaways-from-the-cbo-cost-estimate-of-s-744/)
The CBO report, “The Economic Impact of S.744…” says on p.4, “In sum, relative to current law, enacting S.744 would: …Slightly raise the unemployment rate through 2020,” (http://www.cbo.gov/sites/default/files/cbofiles/attachments/44346-Immigration.pdf)