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Vincent Thian, Associated Press
Taiwan's President and presidential candidate Ma Ying-jeou flashes double V-signs as he's greeted by supporters during a night rally in Taipei, Taiwan, Friday, Jan. 13, 2012. Taiwanese go to the polls to choose their next president on Saturday Jan. 14.

TAIPEI, Taiwan — Candidates in Taiwan's closely fought presidential election appealed for last-minute support Friday, with President Ma Ying-jeou offering his vision of better relations with China, and his main challenger attempting to galvanize resentment over growing income inequality.

Amid swirling campaign banners and cheering crowds, Ma and Tsai Ing-wen of the Democratic Progressive Party crisscrossed the island ahead of a contest that pits Ma's experience against Tsai's populism.

Eighteen million Taiwanese are eligible to vote in Saturday's election, with results expected by about 10 p.m.

Opinion surveys published a week ago — the last permitted under Taiwanese law — showed Ma clinging to a slim 3-4 percentage point lead that was within the statistical margin of error, despite Tsai never having won an election for public office in Taiwan.

A third candidate, James Soong, a former heavyweight in Ma's Nationalist Party, has little chance of winning, though political analysts say he could draw voters away from the president.

Legislative elections being held at the same time are likely to see Ma's Nationalists retain a majority in the 113-seat house, although with a diminished margin.

Ma, a 61-year-old former justice minister and Taipei mayor, is staking his re-election on his success in tying Taiwan's high-tech economy ever closer to China's lucrative markets. During his 3 1/2 years in office, his China initiatives — including opening Taiwan to Chinese tourists and increasing the number of flights across the 100-mile- (160-kilometer-) wide Taiwan Strait — have helped reduce tensions between democratic Taiwan and authoritarian China to the lowest level since they split amid civil war in 1949.

Ma's signature achievement has been the completion of a China trade deal in June 2010 which lowered tariffs on hundreds of goods. While most of Taiwan's $124 billion worth of exports to China last year were electronic goods like television displays and cellphone chips, there was also a big upsurge in agricultural sales from southern Taiwan, long a stronghold of Tsai's party.

Tsai, 55, who has a doctor's degree from the London School of Economics, has acknowledged that the economic aspects of Ma's China policies have received broad support and shows no sign of undoing them. But she has hit out repeatedly at the growing economic inequality she says they have spawned. She has also accused Ma of undermining Taiwan's de facto independence in exchange for economic benefits from China — a claim that resonates strongly with her party's pro-independence base.

There is some evidence that her claims are starting to hit home.

"The economy is the main thing" in the election, said Jenny Wu, the proprietor of a small home wares shop in Taipei. "People will be looking for more opportunities for employment and help for the working class."

Taiwan, one of Asia's economic successes for decades and now a center of high-tech development, has turned in a mixed performance under Ma. Unemployment has fallen in the past two years after reaching a high of 6.16 percent in 2009, and preliminary growth figures for 2011 were a respectable 4.5 percent. But housing prices in urban areas have skyrocketed and the income gap has widened, as large companies that invested in the China trade have profited handsomely from new opportunities.

In the closing days of the campaign Tsai has been moving relentlessly toward the center, promising to open a channel to China to offer assurances that she has no intention of embracing the pro-independence policies of Ma's predecessor, the DPP's Chen Shu-bian. Chen's policies infuriated Beijing, and caused great consternation in the U.S., Taiwan's most important security partner.

Through proxies, Ma has been trying to undermine support for Soong, out of fear that if enough Nationalist backers choose the third-party candidate, the president could lose the election. Some analysts have suggested that if Soong garners 7 percent of the vote or more, Ma will be defeated.

In a separate development, Ma has been buoyed by the arrival of an estimated 300,000 China-based Taiwanese businesspeople, most of whom are expected to vote for the president. Many Taiwanese businesses on the mainland are big Ma backers, and have encouraged their workers to support him.

In the past week police have intensified security for the candidates, mindful of violence during recent Taiwanese polls. In 2004 incumbent President Chen Shui-bian was shot and lightly wounded on election eve — he went on to win by a razor-thin majority — and in November 2010 the son of Taiwan's former vice president was shot in the head while campaigning for a mayoral candidate in suburban Taipei. He has since recovered.

Late Thursday police in the central city of Taichung said they had detained a 65-year-old man who called in a threat to bomb Tsai's local campaign headquarters. They said no explosives were found in the man's home.

And on Friday, police hustled away a knife-wielding woman from outside Tsai's central election headquarters in the Taipei suburb of Banciao.