The Republican-held Senate has passed a bipartisan $4.6bn measure to deliver aid to the US southern border.
The bill has been passed before the government runs out of money to care for thousands of migrant families and unaccompanied children.
The sweeping 84-8 vote came less than 24 hours after the Democratic-controlled House approved a companion measure backed by party liberals that was weighed down by a White House veto threat and bipartisan rejection by the Senate.
Republicans and the White House prefer the Senate measure but House speaker Nancy Pelosi is pressing for quick negotiations to merge the bills — promising that Democrats will not cede to demands to send the Senate bill directly to President Donald Trump without changes.
The Senate vote sent the must-pass legislation measure back the Democratic-controlled House.
Ms Pelosi dismissed speculation that the Democratic-controlled House will simply accept the Senate measure, which cleared a key committee last week with just one dissenting vote. Asked if the House would pass the Senate bill and send it to Mr Trump, Ms Pelosi said “No”.
Ms Pelosi called Mr Trump to discuss the measure.
She told reporters: “There’s some improvements that we think can be reconciled.”
Mr Trump said passing the legislation was urgent as he left the White House for Japan and he appeared to leave the door open for negotiations.
He said: “We are moving along very well with a bipartisan bill in the Senate.
“It’s very far along and I believe the House is also going to also be getting together with the Senate to get something done. It’s humanitarian aid. It’s very important.”
The Democrats should change the Loopholes and Asylum Laws so lives will be saved at our Southern Border. They said it was not a crisis at the Border, that it was all just “manufactured.” Now they admit that I was right – But they must do something about it. Fix the Laws NOW!
— Donald J. Trump (@realDonaldTrump) June 26, 2019
The final outcome is not clear. An impasse could imperil passage of the measure, which is needed soon before federal agencies caring for migrants are hamstrung by lack of money.
Congress plans to leave Washington in a few days for a week-long July 4 recess, and pressure is intense to wrap up the legislation before then.
Failure to act could bring a swift political rebuke and accusations of ignoring the plight of innocent immigrant children who are living in overcrowded, often inadequate federal facilities.