"Our caucus has made it very clear to the Republicans that we will not include funding for the border wall in the appropriations bill that needs to be approved by April 28," Senator Patty Murray stated.
The current budget expires on April 28 and Republicans will need support from Democrats to pass a new spending bill to keep the government functioning.
Top Senate Democrat Chuck Schumer said his caucus had already united against including the border wall in the government budget.
"If anything, our position has strengthened since we've done that," Schumer added.
Trump's 2018 budget blueprint includes $2.8 billion for border security, including the construction of a wall along the southern US border.