Opposition lawmakers on Monday demanded Japan's finance minister resign over allegations he was drunk at a recent summit meeting, creating a new embarrassment for Prime Minister Taro Aso, who is already struggling with approval ratings that have fallen into the single digits.

Japanese media reported Finance Minister Shoichi Nakagawa appeared to be drunk at a press conference following the G-7 finance ministers meeting in Rome last week. Footage of the news conference showed him slurring his speech and closing his eyes repeatedly as if he was dozing off.

Nakagawa said he had taken cold medicine that made him drowsy, but Chief Cabinet Secretary Takeo Kawamura publicly rebuked him Monday and opposition leaders said he disgraced the country and should resign.

"I am ashamed of him," said Ichiro Ozawa, who heads the opposition Democratic Party of Japan. "His responsibility is very heavy."

Nakagawa met with Aso later Monday. Aso said he told Nakagawa to be careful of his health.

"I apologized for the fuss," Nakagawa said. "He asked me to stay on."

The scandal was the latest in a series of embarrassments that have plagued Aso, who has been in office only since September.

In a poll released Sunday by major television network NTV, support for Aso tumbled to just 9.7 percent.

The survey showed nearly three times as many respondents favored Ozawa over Aso as Japan's next leader. NTV conducted the Feb. 13-15 poll through nationwide telephone interviews of 576 randomly selected eligible voters.

Like most Japanese polls, it did not provide a margin of error. But a poll the size of NTV's would generally have a 4.2 percent margin of error.

The poll and the Nakagawa scandal have increased speculation that Aso might soon be forced to step down and call elections for the lower house of parliament. Such elections must be held by the end of September but can be called at any time.

"Mr. Aso should step down immediately, if he hears the voices of the public," said Yukio Hatoyama, a senior member of the Democrats.

Aso's footing had already been shaky after he angered popular former Prime Minister Junichiro Koizumi last week by saying he had opposed the privatization of Japan's postal system — the centerpiece of Koizumi's reforms during his 2001-2006 leadership.

Koizumi, who is still a member of parliament and remains one of Japan's most influential politicians, accused Aso of "firing guns at his fellow lawmakers from behind," adding that "without faith, you can't win elections."

Koizumi's open criticism of Aso was seen as underscoring growing discontent within the ruling Liberal Democratic Party, which has governed Japan for virtually all of the past 54 years. Many in the party fear that it might lose the next elections if they are held under Aso, and they want him to step down before things get worse.

Tomoaki Iwai, a Nihon University political science professor, said Koizumi was trying to set the stage for Aso to resign.

"His comment deepened the party discordance and warned party members to think more seriously about who should take over after Aso," Iwai said.

But Iwai said Aso would have to stay on at least until the main budget for the fiscal year through March 2010 passes, probably in April.