May 31 marks World No Tobacco Day, but the prospect of Japan banning indoor smoking in time for the 2020 Tokyo Olympics looks hazier than ever.

With the last day of the current Diet session looming, the Health, Labor and Welfare Ministry has faced fierce opposition from the ruling Liberal Democratic Party in advancing a bill to curb passive smoking.

In a bid to win support from pro-tobacco LDP members, the health ministry in March watered down its plan to ban indoor smoking in public areas, proposing an exception for small restaurants. Still, the LDP has not shown any signs of making concessions, effectively blocking the government from submitting the bill to the current Diet session, which is scheduled to end June 18.