Taipei mayor Chiang Wan-an is in a weaker position for this year's local election if Huang Shan-shan is not on his side, which is bad news for the KMT in the capital.

• Chiang's re-election math depends on holding together the KMT and TPP voters who backed him last time.
• Huang Shan-shan pulled a big share of that TPP support, and without her the blue-white alliance in Taipei looks shaky.
• The "death cross" is the point where his support falls below a rival's — the warning is that the lines are heading that way.
• A split opposition vote in Taipei hands the DPP a real opening in a race the KMT expects to win.

Outlook: Watch whether the KMT and TPP can agree on a joint Taipei ticket before the November local elections — if not, Chiang's lead keeps eroding.