LONDON — For Prime Minister Boris Johnson of Britain, the political risks of running up the worst death toll in Europe from the coronavirus became starkly clear on Wednesday in a near-empty House of Commons, where he faced off for the first time against the new leader of the opposition, Keir Starmer.
Citing new statistics that suggest Britain, with more than 30,000 deaths, may have overtaken even hard-hit Italy, Mr. Starmer asked Mr. Johnson how he could claim “apparent success” in the response to the outbreak, as he did last week after he returned from his own serious bout with the virus.
“That is not success — or apparent success,” Mr. Starmer said, his words hanging in the silence of a normally boisterous chamber. “Can the prime minister tell us, how on earth did it come to this?”
Mr. Johnson replied that direct country-to-country comparisons were difficult and that the true human cost of the pandemic would only be clear after it was over. While statisticians generally agree with that assessment, Mr. Johnson implicitly acknowledged its weakness as a political argument.
“He’s right to draw attention to the appalling statistics, not just in this country but of course around the world,” Mr. Johnson said.
He tried to deflect attention from the death statistics by throwing out another number: 200,000 virus tests a day by the end of May. That is double the target the government set for April, which it reached on the last day of the month but has since fallen to below 70,000 — a failure that Mr. Starmer also pointed out.
For Mr. Starmer, a human-rights lawyer who was elected leader of the Labour Party last month, it was a sure-footed debut against Mr. Johnson in Prime Minister’s Questions, a weekly ritual that usually unfolds in a rowdy din, as backbenchers whoop for their leader and rain catcalls on the other side.
The pandemic has forced Parliament to allow lawmakers to attend remotely for the first time in its history, leaving Mr. Johnson and Mr. Starmer to face each other as if in a legal deposition rather than a freewheeling political arena.
The quiet setting worked to the opposition leader’s advantage: With a subdued, forensic style, he pressed Mr. Johnson on lethal conditions in nursing homes; shortages of masks and gloves for health workers; and Britain’s decision to abandon testing and contact tracing in the early days of the contagion.
Mr. Johnson was on the defensive partly because his government had presented comparative death statistics at daily briefings since the start of the pandemic. For weeks, as Italy and Spain struggled to contain their outbreaks, the numbers reflected well on Britain. But as the daily number of deaths in those countries has slowed, Britain has quickly caught up.
Measured by the number of officially reported deaths, Britain surpassed Italy on Tuesday by slightly more than 100 people. On Wednesday, with 649 new deaths, Britain reported a total of 30,076 to Italy’s 29,684.
A true comparison is harder to make because of differences in how the countries collect data — Britain recently began including nursing home deaths in its numbers; Italy does not — as well as lag times in reporting deaths outside hospitals. Analysts estimate that the actual numbers in both countries are much higher.
British officials point out that on a per-capita basis, the country still lags behind Belgium, Spain and Italy. But the trajectory is clear: Britain could end up second only to the United States in total fatalities.
So far, the public has been quite supportive of the government. But political analysts said the death toll poses a long-term threat to Mr. Johnson because it is an obvious symbol of what critics call his government’s mishandling of the crisis.
“There is a fairly settled view that we were slow off the mark, and I think that is linked to the fact that our outcomes seem to be worse than those of some others in Europe,” said Stephen Dorrell, a former health secretary who until last year chaired the NHS Confederation, an umbrella group of organizations tied to the National Health Service.
If anything, the prime minister was spared even harsher scrutiny of the death toll this week by a messy personal incident involving one of the government’s most prominent scientific advisers. The adviser — Neil Ferguson, an epidemiologist at Imperial College London — resigned after having admitted he violated a lockdown that he had recommended by illicitly meeting his lover at his home.
The disclosure of Dr. Ferguson’s indiscretion by the Daily Telegraph set off a storm of critical coverage in the right-wing news media, which has vehemently opposed the lockdown. He was nicknamed “Naughty Neil” and criticized as a hypocrite for having failed to abide by the standards he sought to impose on others.
Critics said they were alarmed by the exposure of Dr. Ferguson, which some said bodes ill for other scientists who have delivered difficult advice to the government on the virus and could be penalized for it.
“That was a deliberate act to follow him around and see if you can get any dirt on him,” said David King, a former chief scientific adviser to the government now at Cambridge University. “It’s a way of pulling down the people who have been in favor, through scientific advice, of taking us into lockdown.”
Dr. Ferguson’s resignation follows that of Scotland’s chief medical officer, Catherine Calderwood, after she made two visits to her second home in defiance of social distancing rules.
Last month, the Johnson government’s housing, communities and local government secretary, Robert Jenrick, drew criticism for having traveled from London to a property he owns in rural Herefordshire during the lockdown.
Journalists have also asked whether Mr. Johnson should have left London to recover at his official country residence, Chequers, and whether his partner, Carrie Symonds, should have joined him there.
With the volume of political criticism growing, Mr. Johnson has sought to change the subject yet again, hinting that there will be some easing of the social distancing measures, starting on Monday.