Virginia Democrats asked the US supreme court on Monday to revive a congressional map designed to boost their party’s chances in November’s midterm elections, turning to the court as Republicans – including allies of Donald Trump – seek to preserve narrow control of Congress.

The case thrusts Virginia into an unusual, mid-decade redistricting showdown, as courts weigh whether lawmakers can remake House districts outside the normal post-census cycle – with control of a narrowly divided Congress potentially hanging in the balance.

Virginia’s top court on 8 May threw out a new electoral map that had been crafted to flip four Republican-held US congressional seats to Democrats , dealing a setback to Democratic hopes of retaking the US House.…