It may take Donald Trump’s entire first term and some additional funding from Congress, but his plan to deport at least 2 million immigrants with criminal records is no pipe dream.

The president-elect might need to employ a loose definition of “criminal” and he’d likely need to target legal immigrants with criminal records as well as those who are undocumented. Immigration experts, however, say the enforcement apparatus Trump would require to reach his deportation goals is in place, and the strategies have already been tested by his predecessors.

“I don’t think it will be difficult for him to get up to 400,000 to 500,000 deportations per year with expansive definitions of who’s a criminal,” said Randy Capps, director of research for U.S. programs at the nonpartisan Migration Policy Institute. “Because the Obama administration did that.”

During President George W. Bush’s final years in office and most of President Barack Obama’s first term, any undocumented immigrant charged with a crime but not necessarily convicted was a deportation priority. Obama issued more lenient enforcement guidelines in 2012 and 2014.

Deporting a green card or visa holder who is legally in the United States is more complicated, but most aggravated felonies — such as murder, rape or drug trafficking — qualify a noncitizen for removal.

In 2013, the Homeland Security Department estimated there were 1.9 million convicted noncitizens living in the United States, which includes both undocumented and legal immigrants. The Migration Policy Institute estimates that 820,000 of those are unauthorized; of those, only 690,000 would qualify for deportation under Obama’s 2014 policy targeting those with felonies and serious misdemeanors.

About 2.5 million people were deported from fiscal 2009 to fiscal 2015, roughly half of whom were convicted of a crime, according to U.S. Immigration and Customs Enforcement. But the Obama administration has also released thousands of convicted immigrants, including more than 86,000 in the last three years, according to ICE.

[Can Trump Have It Both Ways on Immigration?]

The DHS figure of 1.9 million is likely what Trump was citing when he appeared on CBS’ “60 Minutes” last Sunday, saying that 2 million to 3 million undocumented immigrants who commit crimes would be deported. But even if Trump opted against deporting legal immigrants with criminal records, he can still target other immigrants whose status is less than criminal but still unlawful.

Jessica Vaughan, policy director at the conservative Center for Immigration Studies, says he could crack down on people who cross the border illegally or skip immigration hearings.

“When you add up all these categories, you’re easily going to get to 3 million,” she said.

Trump could also target immigrants who overstay their visas. These people tend to be harder to locate, but there are plenty of them to choose from — more than half a million people who entered the U.S. via air or sea overstayed visas in fiscal 2015, according to DHS.

Whether Trump will require additional funding to carry out his plan is unclear.

Congress allocated $6.2 billion for ICE in fiscal 2015, when the agency recorded 235,413 deportations, but $5.9 billion in fiscal 2012, when it removed nearly 410,000 people. Each deportation costs an average of $12,500, an ICE official told Congress in 2011.

“At some point you would need more resources,” Vaughan said. “But the basic foundation of the program to identify and remove this huge population of criminal aliens is already in place.”

[Obama Administration Cites Appropriations to Defend Immigration Actions]

For starters, there is the Secure Communities program, which Obama ended in 2014 and replaced with the Priority Enforcement Program. Secure Communities, which ran the fingerprints of all arrested individuals against federal immigration records, was criticized for causing an uptick in deportations of nonviolent offenders instead of the dangerous individuals it was designed to target.

“When Secure Communities was new, throughout the country there were a lot of people picked up on traffic violations in states that had laws that said unauthorized immigrants can’t have driver’s licenses and had made driving without a license a criminal offense that got somebody booked into jail,” Capps said. “It didn’t matter if they had a conviction or not, they’d become deportable.”

Capps suggested Trump could alter the parameters of another Obama enforcement priority — targeting undocumented immigrants who arrived in the country after January 2014.

“They could always expand that to be five years ago or even if they just left it as it is, they’d still get a substantial number of people in that category as well,” he said.

Other steps Trump could take might include bolstering the 287(g) program, named for a section in law that effectively deputizes local law enforcement agencies to enforce federal immigration laws. As of May, ICE had 287(g) partnerships with 32 jurisdictions around the country, and helped identify more than 400,000 deportable immigrants, mostly in jails, from 2006 to 2015.

Senate Judiciary Chairman Charles E. Grassley of Iowa and other Republicans have pressed the administration to expand its 287(g) partnerships. In May, Grassley released a list of 10 local agencies that applied for the program from 2008 to 2012 but were neither accepted nor denied.

Regardless of the strategies Trump chooses to employ, Capps said, the president-elect should avoid getting caught up in a numbers game.

“There’s a danger he could start looking for ways to get to 2 million, and could even revert to random enforcement,” he said.