Virginia voters have approved a redistricting measure that could hand Democrats control of the thinly-divided US House of Representatives, US media report. The state is the latest front in a national battle to redraw congressional districts after President Donald Trump and Republicans initiated a national gerrymandering push aiming to help conservatives maintain a congressional majority.

Democrats in California last year approved a similar measure to change the state's voting districts, with the goal of cancelling gains made by Republicans in redrawn maps in Texas. Virginia's passed amendment will redraw the state's congressional map to flip as many as four House seats held by Republicans.

The redistricting referendum is the most expensive ballot measure in Virginia's history by far, with over $80m (£59m) raised as of earlier this month by groups on both sides of the effort. In his first public comments on Virginia's measure, Trump warned that if House Democrats win a majority in the midterm elections, it's going to be a disaster.

States usually redraw their voting maps once every decade after new population data is released as part of the US Census. Texas became the first state to launch a mid-decade change amid pressure from Trump, starting a trend for other states to alter their maps to benefit their political parties. As the political landscape shifts, this upcoming election could have significant implications for control of Congress.