Immigration reform has been at the center of the 2016 presidential election, as many of the Republican candidates continue to use xenophobic language to prove their dedication to cracking down on illegal immigration. The GOP contenders have also resorted to attacking one another to stand out as the candidate with the toughest stance on the issue.

Last month, Republican front-runner Donald Trump released an ad insinuating Sen. Ted Cruz has flip flopped on immigration. While on the campaign trial, the Texas senator has vowed to stop illegal immigration by building a wall on the southern border and by increasing border security with surveillance and biometric technology.

However, the ad, titled "Clear Difference," points to Cruz's support for the bi-partisan 2013 "Gang of Eight" immigration reform bill, which would have given undocumented workers a pathway to citizenship.

The ad, released weeks ahead of the Feb. 20 Republican South Carolina primary, also labels Cruz "pro-immigration" and "pro-amnesty."

"I want immigration reform to pass ... and that allows those here illegally to come out of the shadows," said Cruz at a May 2013 Senate Judiciary hearing in the ad.

Another clip shows the congressman stumbling over his words when asked to explain the amendment he proposed to the controversial bill.

"Of course I wanted the bill to pass -- my amendment to pass. ... What it doesn't mean is that I supported other aspects of the [2013 immigration reform] bill," Cruz said.

Cruz later argued he introduced the amendment as a poison pill to derail the comprehensive reform bill championed by immigrant activists.

The ad ends by showing Trump taking a definitive stance to curb illegal immigration during a previously recorded interview with ABC.

"People want to take back their country. We want to do it in a humane way, but we don't have a country. We don't have a country right now," said the billionaire businessman. "People are pouring in, pouring in, and they're doing tremendous damage if you look at the crime, if you look at the economy."

Despite his claim that Cruz has flip flopped on immigration since 2013, Trump also makes the false assertion that undocumented immigrants are "pouring" across the U.S.-Mexico border, resulting in more crime in the U.S.

Data shows the flow of illegal immigration has been steadily decreasing and has even fallen to its lowest level in 20 years. A report released by the U.S. Department of Homeland Security earlier this month shows the number of illegal crossings at the U.S.-Mexico border dropped by 36 percent from December to January. This indicates there were fewer immigrants attempting to cross the southwest border. Plus, the government's controversial deportation raids are helping to decrease and deter the number of undocumented immigrants crossing the border.

In addition, there is no solid evidence to support Trump's claim that an influx of crime from Mexico is occurring.

In turn, Cruz has fired back at the real estate mogul, pointing out his stance on immigration has also evolved over the years. Cruz highlighted a criticism Trump made in 2012 of then GOP nominee Mitt Romney for calling for "self-deportation." Cruz also attacked Trump for sending a tweet in 2013, saying, "Amnesty should be done only if the border is secure and illegal immigration has stopped."

Watch "Clear Difference" below: