A spending plan pushed by congressional Republicans is "ridiculous" because it does not include funding for a border wall with Mexico, President Donald Trump said Thursday.

   Trump tweeted that he wants to know "where is the money for Border Security and the WALL in this ridiculous Spending Bill," adding that "REPUBLICANS MUST FINALLY GET TOUGH!"

   Trump's outburst could complicate GOP efforts to delay a potentially messy fight over border funding until after the midterm elections in November.

   The Senate on Tuesday approved a bill that funds the military and some civilian agencies for the next year and provides a short-term fix to keep the government open through Dec. 7.

   The stopgap bill would not address Trump's long-promised wall along the U.S.-Mexico border, although separate spending bills being considered in the House and Senate provide funding for the wall. GOP leaders have said they prefer to resolve the issue after the Nov. 6 elections.

   Trump cited an opinion column by Sen. David Perdue, R-Ga., blaming Democrats for the failure to fund the wall.

   "The thing that's lacking is we can't properly secure the border because of the Democrats' historic level of obstruction," Perdue wrote.

   Perdue said that while Congress has made progress on spending bills, GOP leaders decided to roll its unfinished work into a package tied to defence funding and "call it a day" until Dec. 7.

   "This a total sleight of hand. It is caving to Senate Democrats who are doing everything they can to derail President Trump's agenda, including funding for border security and the wall," Perdue wrote in the Washington Examiner.

   Perdue was one of seven senators who opposed the stopgap bill approved by the Senate. The House is expected to approve the bill next week, days ahead of a Sept. 30 deadline for a government shutdown.

   A Republican aide, who was not authorized to speak publicly and asked not to be identified, dismissed Trump's tweet as "just saber-rattling" and said it would not derail efforts to avert a government shutdown at the start of the new budget year Oct. 1.

   Despite Trump's frustration at the lack of funding for the wall, his tweet hints that he will eventually sign the stopgap bill by asking where money for the wall will come from "after the Midterms?"

   A bill being considered in the Senate allocates $1.6 billion for Trump's wall next year, far short of the $5 billion that Trump is seeking. A bill approved by a House committee includes $5 billion for physical barriers and associated technology along the U.S. southern border.