A new poll shows the DPP's Su Chiao-hui pulling ahead of the KMT's Lee Shih-chuan in the New Taipei City mayor race, a warning sign for the KMT after 21 years running the city.

• Su has climbed steadily in both support and expected-winner numbers, while Lee has stayed flat.
• Momentum matters because undecided voters tend to swing toward whoever looks like the winner.
• Almost 45% of those polled want a change of ruling party in New Taipei, a demand the KMT can no longer claim as its own.
• A DPP campaign headquarters launch on September 5 is being pitched as the next test of that momentum.

Outlook: With about 90 days left, the race is close enough that one big event could break it open in either direction.