Sessions believes the influx in the number of immigrants is too large, and "has created great stress on the job prospects and wages of Americans." That group includes immigrants seeking permanent residency as well as those now in the U.S. on guest worker visas.
"The plain truth is that technology and robotics advance the quality of our lives and lowers the cost of products, but they eliminate many good jobs," said Sessions. "At this point in time, our economy cannot sustain the current lawful rate of immigration, much less the illegal flow."
Sessions has endorsed Donald Trump, the billionaire businessman running for the GOP presidential nomination who favors reduced levels of immigration.
Sessions has in the past held hearings on the H-1B visa and its impact on the technology workforce, and has criticized the use of visa workers in the wholesale replacement of IT department workers.
At Wednesday's hearing, the committee focused on the broader spectrum of immigration, from permanent residency to guest workers.
Sessions cited Pew Research Center data that found -- after the passage of the Immigration and Naturalization Act of 1965 -- the nation's foreign-born population increased from 9.6 million, or 5% of the population, to 45 million in 2015, or 14%.
"In general, when immigrants come in, those who compete with immigrant workers will tend to do a little worse off, and those who use immigrant workers or compliment immigrant workers tend to do better off," said George Borjas, a professor of economics and social policy at Harvard, who testified at the hearing.
"Somebody's lower wage is somebody's else's higher profit," said Borjas, who said that what immigration really does is redistribute wealth.
Also testifying was Steven Camarota, director of research at the Center for Immigration Studies, an organization that favors lower immigration rates. He said there is no question that immigration leads to a larger economy, but a larger economy, by itself, is not a benefit to Americans, "in the same way that Mexico has a larger economy than Norway."
There is no research indicating that immigration significantly increases the income of native born residents, said Camarota.
Benjamin Johnson, executive director of the American Immigration Lawyers Association, also testified and argued in support of immigration. Johnson said immigrants "helped build and invent the industrial era, the atomic age, and now the computer age."
Despite the "overwhelming evidence" that immigration has helped the U.S., Johnson argued that our history "has been repeatedly sullied by periods of fear and anger" and blame toward immigrants over social and economic challenges.