Sunday’s sweeping victory by the Liberal Democratic Party-New Komeito ruling bloc in the Upper House election put an end to the divided Diet and hopefully to the “revolving door” of prime ministers over the past seven years, as ridiculed by foreign media.

That is at least until the next Lower House election, which must be held within the next three years.

But even though the ruling bloc secured a majority in the Upper House, the first time since the LDP’s defeat in the 2007 election during Prime Minister Shinzo Abe’s first stint at the nation’s helm, he is not expected to rush into revising the pacifist Constitution, experts said, noting his priority will instead be boosting the fragile economy.

The LDP-New Komeito bloc secured a majority in the chamber but not the two-thirds majority it will need to revise any clause in the Constitution before the agenda is put to a national referendum, as stipulated under Article 96. Abe hopes to revise the article — if he can garner enough votes — so that only a simple majority would be needed to amend the national charter.

Abe has a full agenda without including the constitutional revision, said Sadafumi Kawato, a University of Tokyo professor of political science. “Abe has three years to achieve his (right-leaning policy) goals.”

But Abe said Sunday night after the polls closed that he will gradually start discussions on amending the Constitution.

“We need a majority in both Diet chambers to revise” Article 96, Abe said. “Since we were granted political stability, we will calmly deepen the debate.”

Indeed, Abe needs the cooperation of the opposition camp, namely Nippon Ishin no Kai (Japan Restoration Party) and Your Party, because New Komeito, which is backed by the pacifist Buddhist lay group Soka Gakkai, opposes his quest to revise Article 96 because this would make it easier for him and the LDP to amend the war-renouncing Article 9.

Proponents of the constitutional revision including the LDP, Nippon Ishin and, previously, Your Party, currently have 63 uncontested seats in the Upper House but need another 99 to have the necessary two-thirds vote to revise Article 96. However, Your Party dropped its support for revising the article just before the campaign kicked off, saying there are other priorities.

Koichi Nakano, a professor of political science at Sophia University, said Abe may try to break up the Democratic Party of Japan, which suffered another devastating defeat Sunday after being ousted from power in the Lower House election last December, by getting some DPJ members to support a constitutional revision.

The DPJ opposes revising Article 96 but does not have a unified stance on Article 9, which bans the use of force to resolve international disputes.

“DPJ lawmakers such as (former Prime Minister Yoshihiko) Noda were once called the LDP Noda faction, as their views are very similar to the LDP’s, especially on the Constitution and on collective self-defense,” said Nakano. “It is possible Abe may try to split the party by bringing the constitutional revision to the table.”

Even though Abe as LDP president has seen his party win two landslide election victories in a row, he faces an uphill battle in tackling key economic issues, including keeping momentum in his economic policies dubbed “Abenomics,” deciding whether to raise the consumption tax next spring and steering the negotiations for the U.S.-led Trans-Pacific Partnership trade pact.

Any one of these issues could shatter Abe’s power base and his support rate, which is around 60 percent in media polls.

Past internal LDP power struggles when it was in power show that if the Cabinet support rate starts to fall, party ranks will jockey to replace their leader, and hence the prime minister.

Hiking the 5 percent consumption tax to 8 percent next April could be one move that backfires on Abe & Co. His government has said it will make a judgment in October on whether to raise the levy.

Abe has said his administration will base its decision on economic indicators, but hiking the tax, which many see as needed to ease the national debt, could anger voters.

The LDP was in control when the tax was introduced in 1989 and when the levy was hiked to 5 percent in 1998, and the party suffered at the hands of voters.

The late Noboru Takeshita was at the helm in 1989 and the LDP lost its Upper House majority after he introduced the then-3 percent tax — Japan’s first such levy. The party lost its Upper House majority again when the late Ryutaro Hashimoto ushered in the hike to 5 percent in 1998.

The TPP, whose negotiations Japan will officially join on Tuesday, is also a minefield for the LDP because of the free-trade pact’s perceived threat to the nation’s farmers, historically a major voting force for the LDP.

Even though the LDP campaign platform said Japan will not unconditionally scrap tariffs on agricultural staples, including rice, wheat, sugar, pork and beef, U.S. Trade Representative Michael Froman last week ruled out any exceptions before Japan joins the negotiations.

“When the LDP wins big and party lawmakers increase, it will be harder for its leaders to control every member,” Nakano said. “It will make it harder for the party to reach an agreement.”

Abe also faces the challenge of pushing economic reforms such as deregulation.

Two of the “three arrows” of Abenomics — big fiscal spending and aggressive monetary easing — have cast the impression that Abe can revive the moribund economy, but foreign investors, who account for more than 50 percent of Japanese stock trades, have doubts that Abe can achieve deregulation if he faces stiff resistance within his party.

“Foreign investors will be watching (to see) how fast and how hard Abe tries after the election to make big structural and regulatory changes that will really open up the economy to new kinds of domestic competition and foreign competition,” said Scott Seaman, a senior analyst at Washington D.C.-based Eurasia Group.

“Abe needs to accomplish a lot to impress foreign investors and make them think that a sustained economic improvement in Japan is possible, especially given a shrinking population.”

Sunday’s election may have brought political stability, but it effectively ended the two-party system of the LDP and DPJ that was envisioned with the introduction of the single-seat constituencies in the 1996 Lower House election and culminated with the DPJ’s victory in the 2009 Lower House race that ousted the LDP from power.

Exit polls Sunday suggest the DPJ secured the fewest seats since it was established in 1998.

Experts believe it will take years for the DPJ to rebuild, if possible, while Your Party and Nippon Ishin will be seen as mere small copies of the LDP.

Critics also say the ever-strong LDP harkens to the situation that started in 1955, when the party ruled alone until losing its Lower House majority in 1993.

The only difference from 1955 is that Japan lacks strong opposition parties like the then-Japan Socialist Party, which served to check the LDP’s power, said Nakano of Sophia University.