 -- Vermont’s independent Sen. Bernie Sanders has positioned himself to the left of front-runner Hillary Clinton on several key issues, ranging from climate change to minimum wage, but his recent comments on immigration are giving some activists pause.

In a series of interviews this week, Sanders defended his decision to vote against a comprehensive immigration bill in 2007, arguing he was concerned about increases in temporary worker visas and the potential effect immigration could have on wages and jobs. He did, however, vote for a 2013 immigration bill after he was able to secure funding to fight youth unemployment in this country.

“Absolutely, we need a path to citizenship for undocumented workers,” Sanders told ABC News’ Jonathan Karl on “This Week” Sunday. “We need to take people out of the shadows.

“What my concern then was -- and remains -- is these guest worker programs,” Sanders, 73, continued. “Where you have folks in high-tech jobs getting fired, while the corporations are bringing people from Russia and other countries into the U.S. to replace American workers and drive wages down.”

That idea has been widely disputed by economists from both sides of the aisle, including Jason Furman, chairman of Council of Economic Advisers for President Obama. Furman wrote in 2012 that “increased immigration to the United States has increased the earnings of Americans with more than a high school degree.”

And it is not just skilled labor that Sanders talks about. He told Univision’s Jorge Ramos this week he has concerns with expanding the immigration of unskilled laborers, too.

“When you have 36 percent of Hispanic high school graduates who are unemployed, 51 percent of African-American kids who are unemployed, do I think it’s a good idea to open the border and bring in unskilled workers? No, I don’t,” he said during an interview that aired Sunday.

Cristina Jiménez, managing director of United We Dream, one of the nation’s largest youth-led immigration advocacy organizations, told ABC News that on the issue of immigration, Sanders seems a bit “disconnected from reality.”

“This idea that immigrants could hurt the economy and depress wages; not only is that hurtful to our community, it is not even true,” she continued.

Sanders was pressed last week on the issue while participating in a Q&A with the Hispanic Chamber of Commerce. “My father was an immigrant [from Poland]; immigrants have built this country,” the Brooklyn, New York-born senator said. “That is one of the virtues of America; that we have people coming from all over the world with their own particular set of skills and ideas.

“That is what makes America a unique country, and something that we should be very proud of.

“But there is a great difference in saying, ‘We welcome immigrants and that were going to provide a path towards citizenship for those people and those families that are in the country today,’” he continued. “Then saying, ‘Oh, were not going to have any borders at all.’”

The primary focus of Sanders’ campaign remains unemployment and income inequality in this country. On many social issues he is quick to pivot back to statistics about unemployment and low wages.

Since announcing his campaign three months ago, he has successfully mobilized an impressive grassroots campaign, turning out thousands to his rallies across the country and signing up over 100,000 people online to attend local house parties for him this week, according to the campaign. Still, if recent elections are any indication, presidential candidates seeking the Democratic nomination must gain support of minority voters.

After moderating the Q&A, Hispanic Chamber of Commerce President and CEO Javier Palomarez said he did not think Sanders’ positions on a few immigration policies would ultimately costs him votes.

“I don’t think there is a single candidate that the Hispanic community today is going to agree with 100 percent,” Palomarez said.

“Is immigration important? Absolutely, is it a unifying issue, absolutely, but it is not the only issue.”