President Barack Obama is the boss-buster in chief when it comes to going after employers who hire undocumented workers, according to U.S. Rep. Debbie Wasserman Schultz, D-Weston.

“President Obama has the most border patrols and border security deployed at the border of any previous president,” said Wasserman Schultz, in a June 20 interview on MSNBC. Obama “has cracked down on employers who are attracting undocumented immigrants and hiring them more than any previous president.”

In a related fact-check, we gave Wasserman Schultz, who also serves as the Democratic National Committee chair, a Mostly True for her claim about border patrol and security. Here, we will explore if Obama holds the record for cracking down on employers who hire undocumented immigrants.

For some background, we turned to the Migration Policy Institute, a think tank that studies worldwide migration. Its 2013 paper about the history of immigration enforcement includes a chapter on workplace enforcement. We also found some background in a 2010 investigation from the Orange County Register.

After multiple efforts, Congress passed the 1986 Immigration Reform and Control Act, which stated that employers couldn’t knowingly hire unauthorized workers. Employers must attest that they made a good-faith effort to verify the eligibility of workers by completing an I-9 form.

The documents are easy to counterfeit, so the federal government developed an online employer verification system in the 1990s under President Bill Clinton, and the use of it soared after 2007. That system, now known as E-Verify, is currently voluntary, though some states mandate it for certain employers. (The Corker-Hoeven amendment to the Senate immigration bill would make it mandatory.) E-Verify spending dramatically increased under President George W. Bush and Obama.

Still, immigration rules have proved difficult to enforce. As of 2010, about eight million unauthorized immigrants worked in the United States.

The federal government’s worksite enforcement strategy has changed over time as well, making it difficult to compare data and declare any president the leader in cracking down on employers, experts across the political spectrum told us.

At times, members of Congress have called for stiffer workplace enforcement. But when the reality hit home in their districts and led to complaints from business owners, politicians urged the federal government to ease up, according to border expert and University at Albany Professor Rey Koslowski. That’s why border security has been more politically popular to fund than worksite enforcement. (We should note that a significant percentage of people working illegally don’t cross the border; they simply overstay their visas.)

Doris Meissner, the Immigration and Naturalization Service commissioner under Clinton, called worksite enforcement “a bit of a third rail.” (She is one of the authors of the Migration Policy Institute paper. The Immigration and Naturalization Service is now called Immigration and Customs Enforcement, known as ICE.)

Under Bush, workplace raids on factories and meatpacking plants received much attention. But after Obama took office, the Department of Homeland Security unveiled a new strategy and ditched the workplace raids, which also tended to punish employees, in favor of “paper raids” — I-9 paperwork audits of employers to determine if they complied with employment eligibility verification laws.