Japanese Prime Minister Shinzo Abe has vowed to stay on, a day after he hinted he may quit if Japan's mission in Afghanistan was not extended.
Mr Abe has staked his job on this latest battle
Mr Abe has faced growing calls for his resignation, but said he was intent on staying to push through his reforms.
On Sunday, Mr Abe staked his job on extending Japan's support of the US-led mission in Afghanistan, beyond a current November deadline.
The opposition is against the mission and could delay enactment of the bill.
Mr Abe said on Sunday he had "no intention of staying" on as leader if MPs blocked the move, prompting some analysts to suggest he could be seeking an honourable excuse to step down.
Mr Abe has been facing calls to resign ever since his Liberal Democratic Party suffered a crushing defeat in July's upper house election.
The result was partly blamed on a series of scandals involving his ministers.
"I am well aware that there is a view that I should step down," Mr Abe told lawmakers on Monday, in a policy speech at the start of a two-month session of Japan's parliament.
He said he would respond to the negative criticism by pressing ahead with reforms.
"We need to depart from the post-war regime by all means. I decided to stay on out of my sheer belief that we must not stop this reform," he added.
He also reiterated comments he made over the weekend, in support of extending Japan's naval mission to help US-led operations in Afghanistan.
"Is it really alright to withdraw now, and abandon our responsibility in the international community?" he asked parliament.
"I ask for your understanding so that we will be able to continue the operation," he said.
The mission involves Japanese vessels in the Indian Ocean providing refuelling and other logistical support to US military planes, and the US has made clear it sees these activities as vital.
Some critics say Japan's involvement in the mission violates the nation's pacifist constitution, which strictly limits its military activities.
The opposition Democratic Party says Japan should only participate in UN-led peacekeeping missions.