A Democratic Progressive Party legislative leader yesterday stepped up his campaign to end the bickering among the party's presidential hopefuls by vowing to refer those who launched future verbal attacks to a party committee for disciplinary action. DPP caucus secretary-general Wang Sing-nan said the four main DPP hopefuls would not be held responsible for previous verbal thrusts, but insisted that such behavior had to stop. "If they don't have at least some sense of self-restraint, they should not be running for president," Wang said. The four contenders consist of Vice President Annette Lu (呂秀蓮), Premier Su Tseng-chung, DPP Chairman Yu Shyi-kun (游錫<方方土>) and former Premier Frank Hsieh (謝長廷). Wang said that a clause in the DPP's charter stipulates that party members who violate the party's charter or resolutions or who damage the party's reputation are subject to a Central Review Committee disciplinary review. According to another party rule, party members who harm the party or party comrades by making false accusations against them can have their membership suspended by up to two years. The DPP's only asset is unity, which is the main reason it has become a ruling party, Wang said, adding that the party must let the voters know that the party can and will restrain party candidates who attack their rivals. In the future, the caucus will collect evidence against presidential and legislative candidates launching any type of attack against party rivals and refer their cases to headquarters for disciplinary action, Wang said. But one of the party's presidential hopefuls thought the threat was much ado over nothing. Vice President Lu said voicing different opinions is what a primary is all about and accused the party of overreacting by threatening disciplinary action. Review Committee Chairman Kao Jyh-peng said he hoped yesterday's appeal would work and that the panel would not have to decide on whether or not to suspend a fellow party member. Kao also believed that DPP supporters had their own bottom line for this kind of party infighting, and whoever crossed the line would see their popularity ratings drop rapidly. DPP party members will vote in the presidential primary on May 6, after which a series of public opinion polls will be conducted. The vote will comprise 30 percent of a candidate's score and the polls the other 70 percent. The verbal crossfire between the four presidential aspirants has been intense, in part because there are more contenders for the nomination than in the previous two primary campaigns prior to the 1996 and 2000 elections. Among the many verbal jabs that have drawn attention, Vice President Lu attacked Premier Su for allegedly pressuring President Chen Shui-bian (陳水扁) to resign during a massive protest last year. Yu later sided with Lu in repeating the accusation, but Chen later said the charge was blatantly untrue. Frank Hsieh and Premier Su sniped at each other over opinion poll results aired by a local TV station that said Su trailed Hsieh by a wide margin, a result Su labeled as unsubstantiated. Su has also been attacked for his conditional support for the controversial Suao-Hualien Expressway.