Supporters of Taiwan's opposition Nationalist presidential candidate have opened a liaison office in Shanghai, giving party faithful the chance to campaign in mainland China for the first time since 1949.
The Nationalists, or Kuomintang (KMT), deny any direct link with the office, but the news has prompted charges in Taipei that bitter rival China, which regards Taiwan as a rebel province, is meddling in the island's March 20 presidential polls.
The head of the Shanghai office, Edison Yeh, denied that he was being used.
"It's every Taiwanese person's democratic right to vote. We're here to make sure they exercise that right," Yeh told Reuters on Tuesday.
"We're just a group of like-minded people who love Taiwan," said Yeh, whose spartan office lies just across from the Peace Hotel on Shanghai's historic waterfront Bund.
The Nationalists, for decades China's legal government, fled to Taiwan in 1949 after losing a civil war to the communists. They ruled the island, in the name of the Republic of China, for the next half-century before Chen Shui-bian of the pro-independence Democratic Progressive Party (DPP) swept to power in 2000.
China insists Taiwan must be brought back to the fold, by force if necessary, but despite the diplomatic sabre rattling, trade is booming. Taiwan companies are estimated to have invested up to $100 billion in the mainland and one million Taiwanese, many of them potential voters, live in China.
"We have nothing to do with the office there," KMT spokesman Alex Tsai said in Taipei. "It was set up by businessmen. The KMT has made clear it will not set up such an office in the mainland because the DPP can easily attack us as being pro-Communist."
Yeh is at pains to point out that his office has not been officially sanctioned by KMT headquarters in Taipei.
"We have not been in touch with them. We are just a group of volunteers who want better relations with the mainland," he said.
The 40 to 50 volunteers who work in the Shanghai office man the telephones night and day, lobbying Taiwanese in China to vote for Nationalist Party chairman Lien Chan, Yeh said. They also help organise groups to fly back to the island for the election.
Due to the sensitivity of having a pro-Kuomintang office in communist China, Yeh said the volunteers kept their activities to a minimum, not organising meetings or even discussing politics.
The Chinese government "has never said they approve or disapprove of us being here. But they probably know about us", said Yeh, who has given up a highly paid consulting job to work for the campaign.
No Taiwan flags are on show in the office, in deference to Chinese law which bans display of the red, white and blue emblem.
Taiwan opinion polls suggest many favour Lien and running mate James Soong over incumbents Chen and Vice President Annette Lu.
While the Nationalists have accused Chen of provoking Beijing to secure votes from core pro-independence voters, the DPP says the opposition is willing to sacrifice Taiwan interests just to gain access to the mainland's vast market and cheap labour.
Yeh said the Shanghai office was rented by former Taiwan justice minister Liao Cheng-hao, and was originally set to house a school for children of Taiwanese businessmen in the mainland.
"We have to keep low key to avoid accusations we are selling out Taiwan," Yeh said.
Chen's campaign spokesman, Wu Nai-jen, questioned whether the Nationalists had made a secret deal with mainland China in order to secure its blessing for the Shanghai office.
"Everybody knows that China has imposed many restrictions on even religious activities, not to mention political activities. Moreover, it has banned Taiwan business people operating on the mainland from taking part in any political activities," said Wu.
The irony of campaigning in a communist country that has threatened to use force to recover Taiwan seemed lost on Yeh.
"That's a historical problem. We have to respect each other's history," said Yeh, who first came to China in 1997 as a law student.
And what of Chen Shui-bian's planned referendum, which has so roused the ire of Beijing, which fears the DPP are using it as a cover to declare independence?
"The politics are so complex. We don't talk about that."
The KMT in Taiwan says Lien was furious that the office had been opened, and had demanded that signs in the office reading "Lien-Soong campaign headquarters" be removed.
That would be news to Yeh, whose name card uses those exact same characters. "Please tell everyone about us. We don't want to miss a single vote."