WASHINGTON President Joe Biden on Tuesday announced a new effort to provide a path to citizenship to hundreds of thousands of immigrants in the US illegally who are married to US citizens, an election-year move that contrasts sharply with Republican rival Donald Trump's plan for mass deportations.

At a White House event, Biden criticised Trump for separating migrant families at the US-Mexico border and using incendiary language about immigrants in the US illegally, including comments that they were "poisoning the blood of our country."

"It's hard to believe it's being said, but he's actually saying these things out loud. And it's outrageous," Biden said. "I'm not interested in playing politics with the border or immigration. I'm interested in fixing it."

The new Biden programme will be open to an estimated 500,000 spouses who have lived in the US for at least 10 years as of June 17, officials said on Tuesday. Some 50,000 children under age 21 with a US-citizen parent also will be eligible.

Biden, a Democrat seeking a second term in the Nov 5 presidential election, took office vowing to reverse many of Trump's restrictive immigration policies. But faced with record levels of migrant arrests at the US-Mexico border, Biden has toughened his approach.

Earlier this month, Biden barred most migrants crossing the US-Mexico border from requesting asylum, a policy that mirrored a similar Trump-era asylum ban and drew criticism from immigration advocates and some Democrats.

Biden's planned legalisation programme for spouses of US citizens could reinforce his campaign message that he supports a more humane immigration system and show how he differs from Trump, who has long had a hardline stance on both legal and illegal immigration.

"The Statue of Liberty is not some relic of American history," Biden said. "It still stands for who we are."

The programme will almost certainly face legal challenges and a future president could attempt to end it. Texas Governor Greg Abbott, a Republican whose state has battled Biden in court over immigration policy, said in a statement that the new effort was "blatantly illegal" and "pandering for votes."

The US already provides a path to citizenship for immigrants who are married to Americans and entered the country legally on a visa. But in most cases, those who enter illegally must first leave the US for years before being allowed to return legally.

The new programme will allow the spouses and their children to apply for permanent residence without traveling abroad, removing a potentially lengthy process and family separation. The administration aims to launch the programme in coming months and it remains unclear how long it would take for spouses to obtain permanent residence.

If they are granted permanent residence, they could eventually apply for US citizenship. People who are considered public security threats or who have disqualifying criminal history would not be eligible.

The implementation will roll out in coming months and the majority of likely beneficiaries would be Mexicans, Biden officials said on a call with reporters.

Mexico's President Andres Manuel Lopez Obrador on Tuesday said the decision to regularise Mexican families' migratory status in the US is "very good news", celebrating Biden's announcement during a press conference.

Biden's White House remarks were tied to the anniversary of the Deferred Action for Childhood Arrivals programme.

Former president Barack Obama and then-vice president Biden launched the DACA programme in 2012, another major legalisation effort that currently grants deportation relief and work permits to 528,000 people brought to the US as children.

The Biden administration also announced guidance to make it easier for DACA recipients to obtain skilled-work visas.

DACA enrollee Javier Quiroz Castro joined Biden at the White House and said the programme allowed him to work legally as a nurse in Houston, including during the Covid-19 pandemic.

"It allowed me to live and work and build a family in the only country I have ever known and loved," he said.

Trump campaign spokesperson Karoline Leavitt called Biden's new programme "amnesty" that would create "another invitation for illegal immigration." Trump has highlighted crimes committed by immigrants and has repeatedly pledged to deport millions of people if elected.

A little more than half of US voters back deporting all or most immigrants in the US illegally, Reuters/Ipsos polling shows.

At the same time, separate polling by the advocacy group Immigration Hub found 71% of voters in seven election battleground states backed allowing spouses in the US illegally for more than five years to remain.

Rebecca Shi, executive director of the American Business Immigration Coalition, said focus groups conducted by her organisation with independent and Republican voters found they supported legal status for spouses.

"It boosts turnout in terms of Latino and base voters, but it also has support with the middle and the right," she said on a call with reporters on Monday, adding that most people thought the spouses could already legalise.

One couple who could potentially benefit from the action was eagerly awaiting more details.

Megan, a social worker from the election battleground state of Wisconsin, met her husband, Juan, two decades ago when she worked with his cousin and uncle at a restaurant during her college summer break.

Juan's family, from the Mexican state of Michoacan, had come to the US for generations as seasonal workers, with his grandfather participating in a US programme for farmworkers. Juan was in the country illegally, but she never thought it would be an issue.

"I assumed maybe you pay a fine or something," she said. "The punishment is just totally disproportionate."

They have two daughters now - aged four and seven - and still have not found a way to fix Juan's status. Reuters is withholding their last names because of Megan's concern they could face backlash.

Wisconsin does not issue driver's licenses to immigrants in the US illegally, and the couple worry that Juan, who works as a landscaper, could one day be pulled over and deported.

She said the family likely would uproot and relocate to Mexico if Juan was ever sent back.

"It's just a low-level stress that's always there," she said.

  - Reuters