It seems clear that Dr Tsai Ing-wen will be the next leader of Taiwan's main opposition party. She is, after all, the only candidate so far in the election to choose the head of the Democratic Progressive Party. What is far less clear is if the 57-year-old will represent the party in the presidential election in 2016. To stand any chance she needs to tackle three key challenges. These are persuading the public who want stability in cross-strait relations that the DPP has a credible policy towards the mainland; to carry out reforms within her party which is riven with factional infighting; and to win local elections later this year. Tsai registered her candidacy last week to become the sole contender in next month's election after current chairman Su Tseng-chang and former premier Frank Hsieh Chang-ting withdrew from the race. They wanted to avoid a three-way fight that could intensify divisions in the party. Tsai, the head of the DPP between 2008 and 2012, ran for the presidency in 2012 and was beaten by her Kuomintang opponent Ma Ying-jeou. She later said her defeat was due mainly to voters' desire for cross-strait stability, rather than tensions created with the mainland by former DPP president Chen Shui-bian. For the party to win the presidency, she said, it needed to modify its anti-mainland stance. The governing Kuomintang's policy towards the mainland under Ma has stuck to the principles of the "1992 consensus". This was a tacit understanding reached by the Kuomintang and the mainland during talks in Hong Kong that year the two sides could shelve thorny political issues so that they could pursue talks. It allows the two former bitter rivals to each have their own interpretations of what constitutes China and it is the foundation of the warming cross-strait ties since Ma won the presidency in 2008 with the pledge of closer ties with Beijing. Nationalist forces fled to Taiwan after the civil war on the mainland in 1949, creating decades of enmity between the two sides. The DPP has always rejected this form of consensus, so Tsai must find a way to build trust with the mainland and to reassure the public in Taiwan that stability will be maintained in ties with Beijing. Meanwhile, the student protests over the controversial trade pact with the mainland have undermined the DPP's role as the main focus of opposition to the government. Organisers of the three-week occupation of parliament that ended on April 10 refused offers by the party's leaders to help them oppose the pact. The students found the party as untrustworthy as the Kuomintang in handling the trade agreement, which they claimed would lead to the loss of thousands jobs on the island. They also fear closer ties with the mainland pose a threat to Taiwan's democracy. Tsai must reform her party, and in particular end members' constant infighting. Although Tsai - who became a DPP member in 2004 - has been seen as the "common leader" of all the various factions in the party, it remains to be seen if she is influential enough to rein in the various groupings and party bigwigs, all of whom are more senior than her. The DPP also has to strengthen communication with civic groups, which have gradually emerged as the main force scrutinising and checking the work of the government. The party must win their trust in order to build a consensus - a new approach Tsai has vowed to pursue after registering her candidacy last week. But more importantly for the DPP, she must win the local government elections in November, seen as the prelude to the 2016 presidential poll. If defeated in local elections, party leaders normally step down. If this happens, Tsai's potential crack at the presidency could be over.