TOKYO — Prime Minister Shinzo Abe said Wednesday that his ruling party must win next month's upper house elections to ensure a stable future for Japan after years of indecisive politics hampered by a divided parliament.

Abe said his economic policies, which include monetary easing and higher public spending, had significantly changed Japan's mood since he took office six months ago following the Liberal Democratic Party's sweeping election victory in the more powerful lower house.

The policies, dubbed "Abenomics," have raised share prices and boosted hopes for a sustained recovery.

"Let's bring an end to the twisted parliament through the upcoming upper house elections, and break new ground for Japan's future under a stable government. Let's make a proud Japan," Abe said at a news conference marking the end of the parliamentary session.

The opposition's control of the upper house, where half the 242 seats will be up for grabs in elections planned for July 21, has made it hard for the ruling party to pass legislation. Abe noted that a power reform bill and other bills had been voted down in the upper house, which he called "regrettable."

"The twisted parliament causes indecisive and running astray politics," he said.

If the LDP — along with its smaller, Buddhist-backed coalition partner, the New Komei Party — wins the majority of seats in the upper house, it could control both houses of parliament for the next three years.

The LDP last Thursday announced a campaign platform for the upcoming elections that included revising the constitution, joining a U.S.-led free trade initiative, promoting nuclear power technology exports, strengthening a security alliance with the U.S., and improving ties with China and South Korea.

After his success with his economic policies earned Abe solid public support, he is expected to move on to a wider, nationalistic agenda, including revising Japan's pacifist constitution to allow a stronger military and pushing for school curricula to include the defending of Japan's aggressive wartime actions.

Yet, Abe said that strengthening the economy would remain his main policy goal over the next three years, and warned that it would be difficult to get Japan out of deflation that has dragged on growth for years. The economy grew a stronger-than-expected 3.5 percent in annual terms last quarter, but the Bank of Japan remains far from its target of achieving 2 percent inflation within the next two years.

"Just as we were losing hope that we may never get our economy to grow back, we regained some confidence and think that perhaps Japan can play an active role in the center of the world once again," Abe said.

He also said a strong economy is key to assertive diplomacy. "A country that has lost economic power cannot demonstrate strength in diplomacy," he said.

Earlier this month, Abe announced a series of economic reforms aimed at making Japanese businesses more competitive in what has been called the "third arrow" of his economic recovery program, but investors were unimpressed by the lack of specifics and the stock market has since declined.