The immigration reform bill currently under consideration in the Senate would increase the number of temporary workers in the United States by 1.6 million the year immediately after it passes, according to a report by the Center for Immigration Studies (CIS).

The report, authored by CIS director of policy studies Jessica Vaughan, predicts the number of temporary worker visas the U.S. government issues would more than triple the year after the bill passes. That total would subside slightly the following years, with the number of visas nearly doubling the current number.

Nearly 700,000 temporary work visas were issued in 2012, according to the report.

"These are not insignificant numbers," Vaughan said in a conference call with reporters, saying temporary workers tend to be concentrated in urban areas and in the technology services field. CIS is an immigration policy center that describes itself as "low-immigration, pro-immigrant."

The report comes as the bill, crafted by the bipartisan "Gang of Eight" in the Senate, heads to the Senate floor next week for debate. One of the bill’s vital sponsors, Sen. Marco Rubio (R., Fla.), criticized it Tuesday and called for greater border security measures.

Multiple lawmakers on the conference call praised the report and called for the defeat of the bill. They said the influx of workers would depress wages and make it harder for Americans to find jobs.

"They come in and compete for jobs on a temporary basis with unemployed Americans," said Sen. Jeff Sessions (R., Ala.), one of the bill’s leading critics.

"Fundamentally, we should be putting the interests of American workers first," said Rep. Lamar Smith (R., Texas).

The majority of the initial spike in temporary workers—950,000—would come from the family of immigrants who have ben waitlisted but who would be able to enter the country under the proposed bill. Another large part—220,000—would come from dependents of temporary workers who can enter the country. Both of these numbers would drop in subsequent years, to 95,000 and 50,000 respectively.

The report draws a comparison between the current immigration overhaul bill and the 2007 attempt at immigration reform, when a far smaller increase in the guest worker program was proposed.

"The 2007 bill was defeated in part due to widespread concerns over the increase in the number of guest workers," the report says, although it does not outline the other changes the new reform effort makes at administering the guest worker program.

Vaughan contended that the immigrants entering the country through the guest worker program are "low wage" even though they are largely entering the technology sector, which generally requires education beyond high school.

Most workers are coming in at an entry-level salary and tend to earn lower wages than their native counterparts, she said.

These immigrants depress the wages of American workers, Vaughan and the congressmen said.

Rep. Mo Brooks (R., Ala.) cited an April study by Harvard economist George Borjas that said that illegal immigration has reduced wages for American workers by $99 to 118 billion per year.

This April report also notes that the impact is greatest among high school dropouts, those with the lowest earning potential.

Rep. Lou Barletta (R., Pa.) argued that the increased competition and decreased wages hurts our most vulnerable workers.

"It does not help our legal residents compete for jobs," he said.

Brooks noted that labor participation in the United States is the lowest it has been in over 30 years.

"Immigration is a good thing, but it needs to be smart," Brooks said.

Proponents of the bill questioned the legislator’s arguments.

"It’s not as though the labor in an economy is a fixed pie," said Diana Furchtgott-Roth, a senior fellow at the Manhattan Institute.

She argued that immigrants increase the output of the economy and that their skills complement the native workforce. More immigration will ultimately decrease the unemployment rate, she said.

"More immigrants equals more jobs equals more economic output equals lower unemployment," she said. She contended that her views represent the majority of conservative economists.

Mario Lopez, president of the Hispanic Leadership Fund, echoed Furchtgott-Roth’s comments.

The numbers in the report are only a small percentage of the total workforce, Lopez said.

"Guest workers and native-born workers tend to have complementary skill sets which means that both groups can prosper," he contended.

Lawmakers on the House side of Congress will be the next to tackle immigration reform, if the proposed bill passes the Senate. Many members of the House are skeptical of the Senate’s immigration reform. House Judiciary Committee chairman Bob Goodlatte (R., Va.), for example, has strongly criticized the bill.

Multiple Republican senators, including Sessions and Rubio, went to the House on Wednesday to discuss the immigration bill with the Republican Study Committee, National Journal Daily reported.

Rubio and Sen. Jeff Flake (R., Ariz.) are both members of the "Gang of Eight" that wrote the legislation, while Sessions is continuing his campaign against the bill.

"I’m really worried about the direction we’re going," Sessions said.