The by-election in the City of Chester is the first since the prime minister took office.
The polls have closed in the City of Chester by-election, where voters have been electing a new MP in Rishi Sunak’s first electoral test since becoming PM.
The result, expected in the early hours of Friday morning, will show how the main parties stand following months of political turmoil.
The by-election was triggered by the resignation of Christian Matheson.
The Labour MP quit after Parliament’s watchdog recommended he be suspended for “serious sexual misconduct”.
Mr Matheson admitted he had committed a minor breach of the code and tendered his resignation with “great sadness”.
Although Labour is expected to retain the seat, which it won in 2019 by a majority of 6,164, there will be a focus on the vote share of the parties.
In the last general election, the Conservatives came second in Chester winning 38.3% of the vote, while Labour secured 49.6%.
The Liberal Democrats came third with 6.8% of the vote.
The Conservatives have performed badly in recent by-elections, losing Wakefield to Labour and the historically safe Tory seat of Tiverton and Honiton to the Liberal Democrats.
Those losses increased political pressure on the then-Prime Minister Boris Johnson who later resigned from the role.
Thursday’s by-election is the first to take place since Mr Johnson quit and his successor Liz Truss caused market turbulence with her mini-Budget.
Mr Sunak replaced Ms Truss as prime minister last month and he will be hoping the results offer some optimism for his party, even if they are unlikely to win the seat.
Polls opened across the City of Chester constituency at 07:00 GMT and closed at 22:00.
Nine candidates have put themselves forward to become the area’s new MP.
During her campaign, Labour’s Sam Dixon pledged to stop raw sewage being dumped into the River Dee and said she would fight for local shopping centre Chester’s Row to get world heritage status.
Conservative Liz Wardlaw promised to fight for funding for the Countess of Chester Hospital and improved rail connections to London, Manchester and North Wales.
Liberal Democrat candidate Rob Herd also vowed to protect the River Dee and said he would oppose fracking in the area.