TOKYO — The Olympic Games scheduled to be held in Tokyo this summer may have to be canceled depending on the coronavirus situation, a senior member of Japan's ruling party said Thursday.

The remarks were the first public admission by the ruling party that cancellation or postponement were under serious consideration, though the challenges of holding the Games have become increasingly evident because of a worsening virus outbreak in Japan.

“I want the Games to succeed, but to do so there are a lot of issues that need to be resolved,” Liberal Democratic Party Secretary General Toshihiro Nikai said during a television interview. “If it seems impossible, it needs to be stopped.”

Nikai is the second-most-senior member of the ruling party and a key backer of Prime Minister Yoshihide Suga.

Nikai also said that hosting the Games was a “big chance” for Japan and that efforts should continue to ensure success. But when asked whether cancellation remains an option, he said: “Of course. If the Olympics are going to be the factor causing covid to spread extensively, then what are we holding the Games for?”

“What is most important now is for Japan to gain support from the people,” he added.

Japan recorded more than 4,000 new coronavirus infections Wednesday, its highest total since late January, as it struggles to contain a fourth wave. More-infectious variants of the virus have been gaining ground, especially in Tokyo and Osaka, where they account for more than 80 percent of recent cases.

The medical profession now faces a triple challenge: dealing with a widening pandemic; supervising a planned expansion in vaccinations; and looking after athletes, coaches, officials and spectators at the hottest time of the year.

The head of the Japan Medical Association, Toshio Nakagawa, on Wednesday urged the government to declare a new state of emergency, saying the medical system in Osaka prefecture was beginning to collapse.

There was no immediate reaction from the organizers of the Tokyo Olympics or from the International Olympic Committee, although both have long insisted the Games would go ahead in a “safe and secure” manner.

A senior government official was quoted in the Nikkei business newspaper as saying canceling the Games at this stage was “impossible,” but Jun Azumi, a senior member of the opposition Constitutional Democratic Party, said Nikai’s remarks opened up room for a debate on whether to plow ahead.

Japan’s vaccination program is among the slowest in the developed world. Two months after starting, it has administered just 1.74 million doses, equivalent to one for around 1.4 percent of the population, official figures show.

A weekend opinion poll by Kyodo News found that only 23 percent of Japanese people think the Games should go ahead this summer, while nearly 40 percent said they should be canceled and 33 percent called for another postponement. On Thursday, “canceling Olympics” was trending on Twitter in Japan.

Japan has already banned spectators from overseas from attending the Games and said it will make a decision in May about limits on domestic spectators.

Meanwhile, the torch relay has been beset by virus-related difficulties. The Osaka section unfolded in an empty park outside the city with spectators banned, and other locations have made similar plans. One of the runners tested positive.

On Thursday, the minister in charge of Japan’s vaccination program, Taro Kono, acknowledged that a total ban on spectators at the Games might be inevitable.

“The Games will be held only in a way that it is possible,” he said in a television interview. “This may mean no spectators. It will surely be a different Olympic Games than usual.”

But medical experts say even that might not be enough.

Hiroshi Nishiura, a professor of theoretical epidemiology at Kyoto University who has been advising the government on the pandemic response, wrote this week that a one-year postponement needed to be seriously discussed, including by athletes.

“Just three months before the Games, Japan is facing its greatest crisis,” he wrote in a piece for Bunshun magazine. “I hope the government will make a wise decision.”