By Yoko Wakatsuki and James Griffiths, CNN

(CNN) -- Japanese leader Shinzo Abe has called an early election as he seeks to take advantage of higher opinion polls to secure a third consecutive term as prime minister.

Addressing the country in a national address Monday, Abe said he'll dissolve parliament's lower house on Thursday. A total of 475 seats in the lower house will be up for grabs.

"I've decided I must seek the mandate of the people immediately so I will dissolve the lower house on the 28th of this month," Abe said. He said his decision was influenced by the rising tensions over North Korea.

"We must not give into the threat of North Korea. I hope to gain the confidence of the people in the upcoming election and push forward strong diplomacy," he said.

The country's 48th general election comes after a shaky time for Abe and his government, which was wracked by two corruption scandals linked to the Prime Minister and his wife, and the resignation of defense minister Tomomi Inada over an alleged cover-up.

Abe, who has held power for five years, has seen his popularity fall significantly in the wake of the scandals. His decision to call a snap election, analysts say, is aimed taking advantage of a recent uptick in ratings, thanks largely to the ongoing North Korea crisis and his handling of it. Pyongyang has fired two ballistic missiles over northern Japan in recent weeks.

"In theory, Abe has more than a year left (in office), but he is aware of the fact that his support levels are unlikely to improve much more," said Koichi Nakano, a professor of Japanese politics at Tokyo's Sophia University.

"He has been pushed into a corner by the scandals and he is afraid that once parliament is reconvened, he will face further questioning and another sharp drop in the polls."

Florian Kohlbacher, North Asia director of the Economist Corporate Network, said Abe is also likely hoping to avoid any potential impact the abdication of the Emperor would have on an election next year.

Uncertain standing A Kyodo News poll published Sunday had some good news for the Prime Minister, with nearly 30% saying they would vote for his Liberal Democratic Party (LDP), versus 8% for the main opposition Democratic Party. The prime minister is chosen by both houses of the Diet.

However, a massive 42.2% of respondents said they had not decided who to vote for, setting the ground for a potential swing against Abe.

A large majority of respondents -- 78.8% -- also said they were unhappy with the government's explanation of the land-sale scandal.

Nor were most respondents happy with being asked to choose a new government, with only 23.7% supporting Abe's decision to call an election.

While the opposition has largely struggled to eat into LDP's support, Abe will face a new challenge from a party formed by allies of the hugely popular Tokyo governor Yuriko Koike, who left Abe's party in May.

Koike's Tomin First Party scored a landslide win in recent elections in the capital, taking 79 seats to LDP's 23. The new national party, while not officially linked to her, will likely seek to capitalize on her support in and around Tokyo.

Abe is hoping to take advantage of the "complete disarray" among his main opposition parties, Kohlbacher said, but he warned the risk from the new Koike-linked party "is perhaps higher than Abe thought."

"There is substantial risk for him," he said. "But that risk is only going to grow as the new party forms and develops."

Nakano said the party's potential influence may be overstated however, pointing out that it does not involve any new faces and is likely to take votes from both the LDP and Democratic Party.

Constitutional changes

Any major gains by his opponents could derail Abe's legacy even if he wins a fourth term in office.

Earlier this year, Abe set a 2020 deadline for changing Japan's pacifist constitution, which was imposed on it by the US in the wake of World War II and bars the country from maintaining armed forces.

Abe wants to remove restrictions on the country's Self Defense Forces, the de facto military, as they engage in more exercises and other activity with US and allies amid growing tensions with North Korea.

While his arguments for such a move have been boosted by Pyongyang's missile and nuclear tests, it is opposed by China and South Korea -- who suffered under Japanese colonial occupation -- and only has limited support within Japan, according to recent polling.

"Abe will keep keep a fairly low profile on (constitutional issues) and focus on emphasizing stability and the success of his Abenomics reforms," Kohlbacher said.

Changing the constitution requires a two-thirds majority of both houses of the Diet and a national referendum. At present, the ruling LDP-Komeito coalition holds two thirds of the lower house, 316 seats.

"Abe is aware of the fact that the people do not consider the revision of the constitution a priority issue," Nakano said.

"That's precisely why he is hoping that if he sneaks the issue through in a snap election, he can then say that he has the popular mandate to go ahead with his plans."

Economic wins and woes

As well as the North Korea issue and his desired constitutional changes, the other main plank of Abe's election campaign will be his economic record.

Japan's gross domestic product (GDP) grew at an annualized rate of 2.5% in the three months through June. That was significantly higher than analysts had predicted and means Japan has now recorded six straight quarters of expansion.

Japan had been struggling with falling prices and sluggish growth for decades. Abe's government and the country's central bank responded by slashing interest rates and launching a major stimulus package last year.

However, a major labor shortage remains an issue as "super-aged" Japan sees more and more of its population moving out of its workforce.

This has led some to call for a relaxing of Japan's notoriously restrictive immigration policies to allow more foreign workers into the country.