TAIPEI (Reuters) - Taiwan has appointed as premier William Lai, the mayor of its southern city of Tainan, President Tsai Ing-wen said on Tuesday, as she moved to shore up declining public support. A reshuffle to replace the premier had been anticipated for months as Tsai s approval ratings dropped below 30 percent by August, a private foundation survey showed, from nearly 70 percent soon after her 2016 inauguration.  We have a clear direction for our reforms,  Tsai told a news briefing.  Premier Lai will lead the administrative team, iron out any problems, and take us forward.   Lai s appointment comes a day after the resignation of Lin Chuan, the premier since Tsai took office in May 2016. Frozen ties with China, a massive power outage in the tech hub for Apple Inc and other global firms, a backlash over pension reforms and a revised labor rule, are among the controversies that put pressure on Tsai to replace Lin, as she prepares for her 2020 re-election campaign. Lai, a Harvard graduate, was a lawmaker for four consecutive terms and a whip of Tsai s Democratic Progressive Party (DPP) caucus before becoming in 2010 the mayor of Tainan, home to the plants of Taiwan Semiconductor Manufacturing Co (TSMC) and other technology firms.  I ll redouble our efforts to reform and transform, for the benefit of the people of Taiwan,  Lai said. However, Lai s premiership would not necessarily help the president improve her ratings, some analysts have said.  