Japan's prime minister reshuffled his Cabinet on Monday for the second time this year in a desperate attempt to gain the support of opposition lawmakers as he tries to win quick passage of a bill that would raise the sales tax.

Prime Minister Yoshihiko Noda argues that raising the 5 percent sales tax to 10 percent is necessary for Japan, which faces worsening fiscal problems as its population ages and shrinks and it recovers from last year's earthquake, tsunami and nuclear disasters. But Noda's proposal has generated flak from opposition politicians as well as from within his own party.

Noda — who replaced five Cabinet members, including his defense minister, to satisfy opposition demands — is hoping to pass bills linked to tax and social security reforms before the current parliamentary session ends June 21.

"We are making a major decision that will determine the fate of Japan's future within the next 20 days," Noda told a news conference. "We must overcome the differences between the ruling party and the opposition."

Noda had met Sunday with ruling party legislator Ichiro Ozawa, who opposes the proposed tax increase. The two failed to agree on the bill, meaning Noda would need opposition support to pass it.

Ozawa, who leads a major faction of lawmakers in the ruling party, has said reforms, recovery and cutting waste must come before asking the public to bear a bigger tax burden.

Opposition lawmakers were demanding the removal of four Cabinet ministers, including the defense minister, Naoki Tanaka, whom they wanted replaced because of gaffes and an alleged lack of expertise. They wanted three other ministers — transport, justice and agriculture — removed over separate allegations of misbehavior.

Noda replaced all four of those ministers, as well as the minister for financial and postal reform.

Satoshi Morimoto, a defense and security expert at Takushoku University, was named the new defense minister, becoming the first non-politician to serve the post. Morimoto is known as a media-savvy expert on North Korea and the U.S.-Japan security alliance.

Two of the outgoing Cabinet members — the defense and the land ministers — had been censured by the opposition, which controls the less powerful upper house of parliament and had threatened to reject any discussion about key tax legislation until they were removed.

The five new ministers were to be sworn in later Monday. Twelve Cabinet posts were unchanged.

This is the second time in less than five months that Noda has reshuffled his Cabinet, raising concerns about the stability of his government.

Japan has seen a new prime minister every year for the past six years, with Noda taking office last September.

Even with Noda's move on Monday, it is still uncertain whether the tax bill will pass. There is still opposition from within the ruling party, and it is unclear how much support the bill will get from opposition parties even with the Cabinet reshuffle.

The proposed sales tax increase would come in two phases, rising to 8 percent in 2014 and 10 percent in 2015.