The approval rating for Prime Minister Shinzo Abe's Cabinet has plunged below 40 percent and fallen behind the disapproval rate, amid a deepening scandal linked to cronyism allegations leveled against Abe over a state-owned land sale, a Kyodo News poll showed Sunday.

The support rate stood at 38.7 percent, down 9.4 percentage points from the previous survey conducted before the Finance Ministry admitted to document tampering linked to the cronyism allegations.

A total of 66.1 percent said Abe bears responsibility for the document alteration, while those who thought otherwise stood at 25.8 percent.

But 47.6 percent said Abe does not need to resign over the issue, while 43.8 percent said he should step down.

The latest nationwide telephone survey was conducted Saturday and Sunday, about a week after the Finance Ministry admitted that its bureaucrats doctored documents on the cut-price state land sale in 2016, including by removing references to Abe and his wife.

The revelation has fueled suspicion that the documents were altered to cover up alleged cronyism. Abe said after the allegations first emerged in February last year that he would resign if he and his wife were found to have played a role in the land sale discount of about 800 million yen ($7.5 million).

Abe has denied ordering the rewrite of the documents, but the scandal is apparently feeding public mistrust. The disapproval rate for the Abe Cabinet stood at 48.2 percent, up 9.2 percentage points from the previous survey conducted on March 3 and 4.

The respondents were divided over whether Finance Minister Taro Aso, a key ally of Abe, should resign over the alteration of the official documents, with 52.0 percent in favor of his resignation and 40.4 percent opposed.

A total of 65.3 percent said Abe's wife Akie should be summoned by the Diet to testify, compared with 29.0 percent who said it was unnecessary.

Since Abe commenced his second stint as prime minister in 2012, the lowest support rating recorded was 35.8 percent in July last year, when the government was reeling from a series of scandals, including the cronyism accusations that resurfaced recently.

Asked who should be elected in the next ruling Liberal Democratic Party presidential election in September, Abe was dislodged from top spot by Shigeru Ishiba, a veteran lawmaker and former defense minister.

Ishiba was supported by 25.4 percent of respondents, followed by Shinjiro Koizumi, a rising star in the LDP and a son of charismatic former Prime Minister Junichiro Koizumi. Abe fell to third from first place in a February survey, securing 21.7 percent of support.

With the LDP working to draw up a revision proposal for the war-renouncing Article 9 of the Constitution, 39.1 percent expressed support for a change suggested by Abe to add an explicit reference to the country's defense forces, while 47 percent expressed opposition.

More than 50 percent expressed opposition to constitutional revision while Abe is serving as prime minister, while 36.0 percent expressed support.

Abe, a conservative politician, has been eager to achieve the first-ever amendment of the Constitution, drafted by the U.S.-led occupation forces following Japan's defeat in World War II.

By party, the LDP remained dominant with 36.2 percent backing, but it was down 3.3 percentage points from the previous survey.

The support rating for the Constitutional Democratic Party of Japan, the largest opposition force in the House of Representatives, edged up 0.4 percentage point to 11.5 percent.

The survey, covering 736 randomly selected households with eligible voters as well as 1,148 mobile phone numbers, obtained responses from 505 and 509 people, respectively.