President Donald Trump reversed himself on Friday, saying he would hold back from declaring a national emergency to bypass Congress and fund his controversial plan to wall off the US-Mexican border.

Trump's fight with Democrats over their refusal to approve $5.7 billion for the wall project has paralysed Washington, with the president retaliating by refusing to sign off on budgets for swaths of government departments unrelated to the row.

On Thursday, Trump warned of murderers and gangsters spreading across the country during a visit to the US-Mexican border to push his demand for a multi-billion dollar wall.

TRT World's Jon Brain reports on the aspirations of those fleeing violence.