Polls opened Thursday in Britain for two special elections that could deliver a new blow to scandal-tainted Conservative Prime Minister Boris Johnson.

Wakefield in northern England and the southwestern constituency of Tiverton and Honiton are both electing replacements for Conservative lawmakers who resigned in disgrace. One was convicted of sexual assault; the other was caught looking at pornography in the House of Commons chamber — an episode he explained by saying he was searching for pictures of tractors on his phone.

Defeat in either district would be a setback for the prime minister's party. Losing both would increase jitters among restive Conservatives who already worry the ebullient but erratic and divisive Johnson is no longer an electoral asset.

“For the Conservatives to lose one by-election on Thursday might be regarded as unfortunate,” polling expert John Curtice of the University of Strathclyde wrote in the Independent newspaper. “However, to lose two might look like much more than carelessness – but a sign of a government that is at risk of losing its electoral footing.”

Johnson was 4,000 miles (6,400 kilometers) away at a Commonwealth summit in Rwanda as voters went to the polls.

He told reporters he would not step down if the Conservatives lose both elections, replying to the suggestion with: “Are you crazy?”

“Governing parties generally do not win by-elections, particularly not in mid-term," he said. "That’s just the reality.”

The electoral tests come as Britain faces the worst cost-of-living crisis in a generation, with Russia’s war in Ukraine squeezing supplies of energy and food staples at a time of soaring consumer demand while the coronavirus pandemic recedes.

Johnson won a big majority in a 2019 general election by keeping the Conservatives’ traditional voters — affluent, older and concentrated in southern England — and winning new ones in poorer, post-industrial northern towns where many residents felt overlooked by governments for decades,

Thursday’s elections are a test on both fronts. Rural Tiverton and Honiton has voted Conservative for generations, while Wakefield is a northern district that the Tories won in 2019 from the left-of-center Labour Party.

Opinion polls suggest Labour is likely to regain Wakefield, which would be a boost to a party that has been out of office nationally since 2010. Labour leader Keir Starmer said victory there “could be the birthplace of the next Labour government.”

Polls suggest the Tiverton race is neck-and-neck between the Conservatives and the centrist Liberal Democrats. The leader of the Liberal Democrats, Ed Davey, said residents were “fed up of Boris Johnson’s lies and neglect.”

“Families are facing soaring petrol bills and food prices, and this government’s only answer is to hammer them with constant tax rises,” Davey said.

Even if the Conservatives lose both seats, Johnson retains a large majority in Parliament. But defeat would further erode his crumbling authority among his own lawmakers.

Allegations about his judgment and ethics have buffeted the prime minister for months, culminating in a scandal over parties held in government buildings during Britain’s coronavirus lockdowns.

Johnson was one of 83 people fined by police for attending the parties, making him the first prime minister found to have broken the law while in office. A civil servant’s report on the “partygate” scandal said Johnson must bear responsibility for “failures of leadership and judgment” that created a culture of rule-breaking in government.

He survived a no-confidence vote by his own party this month but was left weakened after 41% of Conservative lawmakers voted to remove him. Johnson could face another rebellion in the coming months.

Polls in the two districts close at 10 p.m. (2100GMT), with results expected early Friday.