Election campaigning in Japan officially started on Tuesday with conservative Prime Minister Shinzo Abe hoping to extend his almost five-year hold on power and fend off a challenge from regrouped opposition forces.

The October 22 snap election for Japan's powerful lower house pits Abe's Liberal Democratic Party (LDP) against the less than one-month-old Party of Hope, led by popular Tokyo Governor Yuriko Koike.

Koike, a former LDP lawmaker and former TV anchorwoman, has shaken up Japanese politics with her new "reformist, conservative" party. Following last month's implosion of the main opposition Democratic Party, a large number of its candidates are now running on the Party of Hope ticket.

Read more: Japan Prime Minister Shinzo Abe calls snap election

In his first official campaign speech, Abe went after the opposition for regrouping and trying to sway voters with catchy, populist slogans.

"What creates our future is not a boom or slogan. It is policy that creates our future," Abe said at a campaign event in Fukushima. "We just cannot afford to lose."

The 63-year-old premier made the decision to call for a snap election at a time when the opposition was weak and fragmented, but the emergence of Koike's Party of Hope could upset Abe's calculations.

Critics say that Abe called for the early election in order to diver attention from a string of recent scandals that have lowered his popularity, including allegations of favoritism to a friend in a business deal.

Strong challenge from Tokyo governor

On Thursday, the media-savvy Koike addressed hundreds of commuters at a bustling station in Tokyo, calling on supporters to "end the politics of Abe."

"The political status quo has continued while politics itself has lost the public's confidence," the 65-year-old governor told the crowd.

Read more: Can Tokyo governor Koike upset PM Abe in snap election?

Koike has criticized Abe's government for being too slow to reform the country and address issues such as Japan's aging population and its mountain of debt.

The Party of Hope, which appeals to conservative voters as well, hopes to distinguish itself from the LDP by pledging a nuclear power phase-out by 2030 as well as a freeze on a planned sales tax hike.

Abe's party hopes to use proceeds from the sales tax hike to make childcare free in a bid to encourage more women to rejoin the labor force.

The Tokyo governor's critics argue that she repeats catchy phrases to garner support and lacks details on how to pay for her ambitious projects. Koike has also repeatedly said she won't run for the prime minister post during this election, focusing instead on running Tokyo with three years to go until the city hosts the Olympic Games. 

Over 1,000 candidates are competing for 465 seats in Japan's lower house. The 12-day campaign will largely focus on reviving Japan's economy and the threat posed by North Korea.

Although Abe's LDP and its coalition partner Komei are expected to win a majority in the lower house, the Party of Hope is on track to snag some seats away.

rs/kms (AP, AFP, Reuters)