Former Irish ambassador to the United States Dan Mulhall has said the Taoiseach should raise the case of Seamus Culleton directly with US President Donald Trump when they meet on St Patrick's Day, if Mr Culleton has not been released by then.
However, Mr Mulhall said he was hopeful Mr Culleton would be released before then.
Mr Culleton, originally from Glenmore in Co Kilkenny, was picked up by Immigration and Customs Enforcement (ICE) agents last September and taken to a detention centre in El Paso, Texas, almost 4,000km from his home in Boston.
While he had previously been undocumented in the US, Mr Culleton, who is married to US citizen Tiffany Smyth, was in the final stages of receiving his Green Card and had a valid work permit.
Speaking on RTÉ's Liveline on Monday, Mr Culleton said he was in fear of his life in the detention centre.
Taoiseach Micheál Martin said yesterday that there were "five to six" Irish citizens being detained by ICE.
Speaking on RTÉ's Morning Ireland, Mr Mulhall said it was surprising that an Irish citizen would be held in detention for so long and that he is certain the embassy is doing all it can on Mr Culleton's behalf.
He explained that when he was an ambassador, the embassy received an annual report list from US authorities about the number of Irish people who had been deported.
This number was always small, he said, and the embassy was also approached separately by a small number of Irish people for whom representations were made.
Mr Mulhall said ICE is now a more difficult proposition to deal with.
"ICE is, shall we say, a more uncompromising organisation than what we've known in the past, and it's probably quite difficult to deal with people who are in ICE detention, because ICE doesn't operate in the way that a normal authority would have operated during my time in the United States," he said.
He said that Mr Culleton's case is gaining international traction and if it gets into the US media environment then it will refute the notion that everyone in ICE detention is a hardened criminal.
This should bring it to a conclusion sooner rather than later, he said.
Mr Mulhall added that it was absolutely untrue to say the Irish embassy has failed to build up contacts with both the Republican and Democratic parties.
You have to have contact with both sides of the political aisle, he said.
Former TD and special envoy to the US John Deasy said yesterday that "this case is a really good example of the lack of contacts that we have in Washington and in America generally".
"Politics doesn't change, it's about contacts, relationships and people knowing who is in power and turning that lever. Unfortunately, we do not have that kind of influence and access we used to have."
In a post on X yesterday, the Assistant Secretary at Homeland Security said Mr Culleton entered the US in 2009 under the visa waiver programme, which allowed him to stay for 90 days without a visa.
Trish McLaughlin said Mr Culleton failed to depart the US after that time.
She said he was offered a chance last September to be "removed to Ireland, but chose to stay in ICE custody".
Seamus Culleton received full due process and was issued a final deportation order from a federal judge.
— Tricia McLaughlin (@TriciaOhio) February 10, 2026
On September 9, 2025, ICE arrested Seamus Culleton, an illegal alien from Ireland. He entered the United States in 2009 under the visa waiver program, which allows you to… https://t.co/EebjCaRBDK
Ms McLaughlin said: "Being in detention is a choice. We encourage all illegal aliens to use the CBP Home app to take control of their departure. The United States is offering illegal aliens $2,600 and a free flight to self-deport now.
"We encourage every person here illegally to take advantage of this offer and reserve the chance to come back to the US the right legal way to live the American dream. If not, you will be arrested and deported without a chance to return."
US halts flights at Texas airport on Mexico border for 'security reasons'
Separately, the US has halted all flights to and from El Paso International Airport in Texas for "special security reasons," the US Federal Aviation Administration said, without giving more details.
The airport, which is next to the US military's Biggs Army Airfield and sits over the border from the Mexican city of Juarez, said all flights had been grounded, in a post on Instagram.
El Paso airport said the restrictions had been issued "on short notice" and it was waiting for additional guidance from the FAA, according to The New York Times.
Flights were also barred from the airspace over the nearby community of Santa Teresa in the US state of New Mexico, the FAA said.
Restrictions would be in place until 21 February and covered a radius of about 10 nautical miles from the airport, not including Mexican airspace, the agency added.
Additional reporting Reuters