security policies (under a different administration) when every single second matters. I'd like (voters) to have the Abe government firmly maintain" power, Koike said.

Experts have been predicting for weeks that the LDP-New Komeito ruling bloc will suffer a major setback in the Upper House election, maybe even losing the majority it holds in the chamber.

If the ruling bloc loses its majority, Abe might be forced to resign over the failure, which some observers feel would spark political chaos.

But Koike, who shares her political destiny with Abe, said he would not need to step down even under such a worst-case scenario.

"This is an Upper House election. He would not need to (resign)," Koike said, playing down the impact of an Upper House poll setback. The ruling bloc holds a majority in the Lower House, which can override the upper chamber when choosing a prime minister.