Trump wants more money for border wall

Richard Cowan and Steve Holland
US President Donald Trump will ask for more money from congress to build a wall at the Mexico border

The Republican-controlled US Congress, riddled by infighting, looks unlikely to act decisively this week on the immigration crisis at the US-Mexico border, providing few answers on what comes next for separated parents and children.

President Donald Trump's abrupt order last week to end his policy of breaking up families who crossed the border illegally did not explain how his aggressive immigration policies could be adjusted to keep families intact, house them and assess their legal status.

The Republican president backtracked amid mounting global outrage, including images of children in cages. He at first urged congress to act quickly and follow up his order with legislation, then he said lawmakers should give up on it.

He returned to a favourite theme on Tuesday and said he will ask congress for an increase in US taxpayer funding for a wall he wants to build along the border with Mexico.

Amid these mixed messages, the House of Representatives was on track to vote on Wednesday on a broad-based immigration bill that would bar the separation of migrant children from their parents. It would also provide $US25 billion ($A34 billion) in wall funding. But the measure was widely expected to fail.

"We've made it extremely clear we want to keep families together and we want to secure the border and enforce our laws," House Speaker Paul Ryan said at a news conference.

Ryan said the broader bill would resolve the issue of young adults who were brought to the US illegally as children; focus on a merit-based immigration system; and secure US borders and the rule of law.

Several House conservatives left a closed-door meeting of Republicans early on Tuesday expressing discontent with the broad bill. Without their support, it will likely be rejected.

Republican Representative Scott DesJarlais, a member of the conservative House Freedom Caucus faction, said he would oppose the broad bill. A separate conservative-backed immigration bill failed to pass the House last week, extending congress' years-long failure to produce immigration legislation.

Ryan said he would not rule out the possibility of bringing to a vote a narrower bill addressing only the detention of immigrant families, if the broader bill did not pass.

Before Trump issued his order last week, more than 2300 children had been separated from their parents under his policy. The government has yet to reunite about 2000 children with their parents, and those youngsters are now scattered across the country, some in foster homes and others in institutions, their whereabouts often unknown to their parents.

Lawmakers concur on the need for ending separations and speeding reunifications, but disagree on Republican attempts to lift a court decree known as the Flores agreement that limits federal detentions of children to 20 days.