Donald Trump has revived a threat to shut down the US government if Congress does not fund his plans to build a wall at the Mexican border, signalling his determination to press his hardline immigration stand in the lead-up to the November midterm elections.

In a Sunday morning tweet, he said: “I would be willing to ‘shut down’ government if the Democrats do not give us the votes for Border Security, which includes the Wall! Must get rid of Lottery, Catch & Release etc and finally go to system of Immigration based on MERIT! We need great people coming into our Country!”

Congress faces a September 30 deadline to pass a budget and avoid a government shutdown after failing to come up with a permanent resolution to the impasse over immigration earlier this year. Since then, the debate on the issue fuelled by Mr Trump’s policies has only grown hotter, thanks to his administration’s widely criticised moves to separate children from their parents at the Mexican border.

Mr Trump has signalled that he wants to fight the midterm elections over two issues that helped get him elected in 2016 — immigration and trade. Many congressional Republicans, however, want to make the main issue a booming economy fuelled by tax cuts they passed late last year.

That economic message, many Republicans fear, could be overwhelmed by concerns over Mr Trump’s trade wars and his threats to shut down the government. Both risk rattling markets in the crucial final weeks before the November 6 midterm elections in which Republican control of Congress is at stake.

His shutdown threat on Sunday also showed how quickly the president can overshadow efforts by his administration and his party to extract maximum political advantage from the strong economic numbers.