US President Joe Biden has accused former President Donald Trump of trying to block legislators from approving an emergency budget bill that includes aid for Ukraine.
The Republican Party has rejected the bill. The party said it would only approve the bill, if measures aimed at strengthening controls along the border with Mexico were established.
A bipartisan group of Senators put together a new bill that would authorize presidential administrations to close the border if the number of migrants claiming asylum became unmanageable.
Biden said on Tuesday that Trump "thinks it's bad for him politically," and "doesn't even know what helps the country."
Trump is the frontrunner to become the Republican Party's nominee in the November presidential election.
He has been trying to discourage party lawmakers from voting for the bill. The former president says it lacks sufficient border control provisions to deter immigrants.
Republican House of Representatives Speaker Mike Johnson says the bill will be "dead on arrival" if it reaches the chamber.