Prominent Liberal Democratic Party lawmaker Seiko Noda struggled Monday to collect enough signatures from fellow party lawmakers in her last-minute bid to run against Prime Minister Shinzo Abe in the party’s presidential race.

Party executives heaped pressure on members not to back her in the Sept. 20 vote as the Tuesday morning deadline for filing loomed.

According to informed sources, Noda had garnered the signatures of 17 LDP Diet members as of Monday afternoon.

However, under party rules, candidates need at least 20 to enter the race.

The tug of war between Noda and the LDP leadership was expected to continue right up to the deadline.

Kochi-kai, an LDP internal faction led by Foreign Minister Fumio Kishida, held an extraordinary closed-door meeting of Diet members Monday, urging them to “remain united” in supporting Abe in the presidential election, according to participants.

With 45 Diet members, Kochi-kai is the ruling party’s third-largest faction.

“We were urged not to break ranks,” one of the participants said.

Makoto Koga, a former leader of Kochi-kai, has been a close ally of Noda — a onetime chairwoman of the LDP’s Executive Council — whom he has repeatedly touted as a potential candidate to be Japan’s first female prime minister. The meeting was apparently arranged to urge members to support Abe, not Noda.

Apart from Noda, Abe is likely to be the only candidate to file papers Tuesday. If he is the lone candidate, the party won’t even bother to hold the election.

On Sunday, Noda crossed off another prerequisite for entering the race by submitting a paper outlining her policy views to LDP headquarters.

All seven of the LDP’s internal factions, which in total cover about two-thirds of the party’s 402 Diet members, have already decided to support Abe, making his re-election almost certain.

Therefore, the decisive factor will be how many nonfactional members will sign their name to support Noda, who is believed to be trying to raise her profile as a possible candidate for a future run for the top spot.

The contents of Noda’s policies paper have yet to be released, but she is believed to be struggling to find areas where she can sharply differentiate herself from Abe.

Noda, regarded as a moderate liberal, has been critical of Abe’s drive to change the government’s interpretation of the war-renouncing Article 9 to allow Japan to exercise the right of collective self-defense. This would allow Japan to use force to defend an ally under attack even if the country itself is not being attacked.

Opinion polls have suggested that a majority of voters oppose the controversial security bills that Abe has submitted to the Diet, one of which is based on the Cabinet’s constitutional reinterpretation.

Noda, however, will find it difficult to capitalize on the public’s frustration with the bills, since she, as an LDP lawmaker, stood with the party in voting for the bills in the Lower House.

“She has already voted for the bills. If she changes her opinion, her credibility as a politician would be questioned,” a high-ranking government official close to Abe said last week.

The official, speaking on condition of anonymity, also claimed that many LDP members fear Noda’s participation in the election could significantly distract the ruling bloc from the Upper House deliberations on the security bills, the Abe administration’s top priority.

A Noda rebellion against the party leadership and criticism of the security legislation would cause a huge public stir, throwing the Upper House sessions into chaos.

Noda, though, has appeared reluctant to cause such a commotion.

Speaking to reporters Saturday in her hometown of Gifu, she claimed that she is not opposed to Abe’s stance on security issues.

“I have voted for the bills. I’m not opposed to the security policies” of Abe, she was quoted as saying by Kyodo News.

Apart from her security stance, Noda — one of a handful of prominent female lawmakers in the LDP — has been known as a strong advocate of women’s rights.

But here again she may find it difficult to differentiate her gender-equality policies from Abe’s since the prime minister, at least on the surface, has styled himself as a strong promoter of female empowerment in Japan’s male-dominated society.

“(Noda) has said that having a presidential election itself is very meaningful,” Tomomi Inada, LDP policy chief and a close aide to Abe, told reporters in Tokyo on Sunday. “But what should be debated is important (as well), and arguments should not be raised just for the sake of argument.”

Staff writer Mizuho Aoki contributed to this report