A widening political scandal is threatening to split Taiwan’s ruling party and set back efforts to build closer economic ties with China.

Recent allegations of influence peddling by Taiwanese politicians, driven in part by investigators’ wiretaps of one lawmaker’s cellphone conversations, have stirred fear and paranoia among some political leaders.

“I’m sorry. It’s not safe to talk right now. We are being monitored,” said a political adviser within the Nationalist Party, whose leaders have both driven the investigation and been the ones most damaged by it.

Taiwan’s justice minister has been forced out, and its high-
profile legislative speaker has been expelled by his party.

The fallout could have sweeping consequences for Taiwanese politics, weakening the already unpopular administration of President Ma Ying-jeou and giving a boost to the opposition party, which is much less friendly toward mainland China.

The dominoes began falling when Taiwan’s high court overturned lawmaker Ker Chien-ming’s guilty verdict on embezzlement charges.

A special investigative unit within the Taiwanese Justice Department subsequently wiretapped Ker’s cellphone, and, according to prosecutors, recorded conversations in which legislative speaker Wang Jin-pyng and Justice Minister Tseng Yung-fu agreed to help Ker ensure that the overturned ruling stuck.

Both Wang and Tseng have denied the charges of meddling, but Tseng has since stepped down, and Wang’s party membership was revoked Wednesday. Wang has vowed to fight his expulsion to keep his legislative position.

At the heart of the growing rift is a long-simmering rivalry within the Nationalist Party between Ma, its chairman, and Wang, a party heavyweight who has held the speakership since 1999. Their rivalry dates to 2005, when both competed to lead the Nationalist Party, also called the Kuomintang. They butted heads again in 2008, competing for their party’s presidential nomination.

This week, Ma called Wang’s alleged meddling in the court case “the most serious infringement in the history of Taiwan’s judiciary.”

Under Ma, Taiwan’s often-fractious relationship with China has hit its calmest point in decades. But Ma has taken a beating in opinion polls and has one of the lowest approval ratings among Taiwanese president. One recent poll has his rating at 11 percent.

The use of wiretapping has angered critics, who say the administration overstepped the constitution to pursue Ma’s politically motivated desire to oust Wang.

Ma’s party has also seen serious erosion in public support as the economy has struggled. And the justice minister’s ouster is at least the fifth cabinet-level resignation this year. The others included a defense minister who left over criticism of an army trainee’s death, a replacement defense minister who left over plagiarism and a premier who resigned partly over the economy.

The expulsion of Wang, who held significant sway in the parliament, could create further roadblocks for Ma’s policy goals, including getting approval for a service-trade agreement with China. Some in Taiwan have opposed the agreement over fears that the island is already too economically tied to the mainland. Wang also had good ties with Taiwan’s opposition party, which has criticized Ma for his handling of the investigation and referred to the wiretapping scandal as “Taiwan’s Watergate.

Liu Liu contributed to this report.