By Ted Hesson

WASHINGTON Former U.S. President Donald Trump, the leading candidate for the Republican presidential nomination in 2024, has promised to crack down on illegal immigration and restrict legal immigration if elected to a second term in office.

Here are some of the policies under consideration:

BORDER ENFORCEMENT

Trump has said he would restore his 2019 "remain in Mexico" program, which forced non-Mexican asylum-seekers seeking to enter the U.S. at the Mexican border to wait in Mexico for the resolution of their cases.

The program was terminated by President Joe Biden, a Democrat who is seeking reelection in 2024. Biden defeated Trump in 2020, pledging more humane and orderly immigration policies, but has struggled with record levels of migrants caught crossing the U.S.-Mexico border illegally.

Trump has said he will seek to detain all migrants caught crossing the U.S.-Mexico border illegally or violating other immigration laws, ending what he calls "catch and release."

Trump focused on building a wall on the Mexico border during his first term and has pledged to close gaps in the border wall if reelected. His administration built 450 miles (725 km) of barriers across the 1,954-mile (3,145 km) border but much of that replaced existing structures.

TRAVEL BANS

Trump has said he would implement travel bans on people from certain countries or with certain ideologies, expanding on a policy upheld by the Supreme Court in 2018.

Trump previewed some parts of the world that could be subjected to a renewed travel ban in a mid-October speech, pledging to restrict people from the Gaza Strip, Libya, Somalia, Syria, Yemen and "anywhere else that threatens our security."

In a mid-October speech in Iowa, Trump focused on the conflict in Gaza, saying he would bar the entry of immigrants who support the Islamist militant group Hamas and send deportation officers to pro-Hamas protests.

Trump said in June he would also seek to block communists, Marxists and socialists from entering the United States.

MASS DEPORTATIONS

Trump has pledged to launch the largest deportation effort in U.S. history.

He aims to deport millions of people living in the country illegally each year, using large-scale roundups and by creating camps to hold them while they await removal, the New York Times reported on Saturday.

The former president would redirect military funds to pay for the deportation effort, the Times reported. Such an action would almost certainly be challenged in court and Congress could potentially restrict use of the funds.

Trump has also vowed to take aggressive new steps to deport immigrants with criminal records and suspected gang members by using the little-known 1789 Alien Enemies Act.

Trump has said he would deputize the National Guard and local law enforcement to assist with rapid deportations of criminals in states that cooperate.

LEGAL IMMIGRATION

Trump said in May he would seek to end automatic citizenship for children born in the U.S. to immigrants living in the country illegally, an idea he flirted with as president. Such an action would run against the long-running interpretation of an amendment to the U.S. Constitution and likely trigger legal challenges.

During his first term, Trump greatly reduced the number of refugees allowed into the U.S. from abroad and has criticized Biden's decision to increase admissions. He would again suspend the resettlement program if reelected, the New York Times reported.

Trump has said he would push for a "a merit-based immigration system that protects American labor and promotes American values." In his first term, he took steps to tighten access to some visa programs, including a suspension of many work visas during the COVID-19 pandemic.

Trump has vowed to end Biden "parole" programs that have allowed hundreds of thousands of migrants with U.S. sponsors to enter the U.S. and obtain work permits, including Ukrainians and Afghans. He has called Biden's programs an "outrageous abuse of parole authority."

He would seek to roll back Temporary Protected Status (TPS) designations, the New York Times reported, targeting another humanitarian program that offers deportation relief and work permits to hundreds of thousands.

Trump tried to phase out most TPS enrollment during his first term, but was slowed by legal challenges. A federal appeals court in September 2020 allowed Trump to proceed with the wind-down, but Biden reversed course and expanded the program after taking office.

FAMILY SEPARATION

In a town hall with CNN in May, Trump declined to rule out resuming his "zero tolerance" policy that led thousands of migrant children and parents to be separated at the U.S.-Mexico border in 2018. Government watchdogs and immigration advocates have found the Trump-era separations - which outraged many in the U.S. and internationally - began before and continued after the policy's official start.

The Biden administration in October announced a settlement agreement with separated families that would offer them temporary legal status and other benefits while barring similar separations for at least eight years.

DACA

Trump tried to end a program that grants deportation relief and work permits to 'Dreamer' immigrants brought to the U.S. illegally as children, but the termination was rebuffed by the Supreme Court in June 2020.

Following the Supreme Court ruling, the Trump administration said it would not accept any new applications to the program, known as Deferred Action for Childhood Arrivals (DACA), and would explore whether it could again try to end it.

Trump again plans to try to end DACA if elected, the New York Times reported.

(Reporting by Ted Hesson in Washington; Additional reporting by Nathan Layne; Editing by Ross Colvin and Rosalba O'Brien)