As tensions fester between China and Taiwan, one elder politician from the island democracy is getting an effusive welcome on the mainland: Ma Ying-jeou, a former president.

Mr. Ma’s 11-day trip across China, which was set to begin on Monday, comes at a fraught time. Beijing and Taipei have been in dispute over two Chinese fishermen who died while trying to flee a Taiwanese coast guard vessel in February, and China has sent its own coast guard ships close to a Taiwanese-controlled island near where the men died.

Taiwanese officials expect China to intensify its military intimidation once the island’s next president, Lai Ching-te, takes office on May 20. His Democratic Progressive Party rejects Beijing’s claim that Taiwan is part of China, and Chinese officials particularly dislike Mr. Lai, often citing his 2017 description of himself as a “pragmatic worker for Taiwan’s independence.”

On the other hand, China’s warm treatment of Mr. Ma, 73, Taiwan’s president from 2008 to 2016, seems a way to emphasize that Beijing will keep an open door for politicians who favor closer ties and accept its conditions for talks.

“Beijing’s policy toward Taiwan will definitely be using more of both a gentle touch but also a hard fist,” Chang Wu-yue, a professor at the Graduate Institute of China Studies of Tamkang University in Taiwan, said in an interview about Mr. Ma’s visit.

Officials from Mr. Ma’s Nationalist Party have hinted that later in his trip, he may meet with China’s top leader, Xi Jinping. That would echo groundbreaking talks that the two held in 2015. China has frozen high-level official contacts since Taiwan’s current president, Tsai Ing-wen, took office in 2016. She and the president-elect, Mr. Lai, belong to the same party, usually known by its initials, D.P.P.

Mr. Lai has said that there will be no drastic change in Taiwan’s status, and that he wants talks with China. But his party rejects Beijing’s conditions for official talks, especially a formula under which each side accepts there is “one China,” even if they differ on what that means. The Democratic Progressives call that a rhetorical trap to advance China’s claim over Taiwan.

Nationalist Party officials argue that they help Taiwan by talking to senior Chinese officials.

“What if an accident happens? There’s no dialogue, no communication channel, between the D.P.P. government and the Communist government in China,” Sean Lien, a vice chairman of the Nationalist Party, said in an interview before Mr. Ma’s trip. “The fact that he’s visiting China in early April, and probably will meet with Xi Jinping — I actually think that will help reduce the mounting tensions between Taiwan and mainland China.”

For Mr. Xi, a meeting with Mr. Ma may be a way of trying to show Chinese people that Taiwan is not slipping irretrievably beyond hope of unification.

“For Beijing, it’s in Xi’s interest to show that time is on mainland China’s side, and maybe he can spin a meeting with Ma — if it happens — to convey that narrative to the domestic audience,” said Bonnie S. Glaser, managing director of the Indo-Pacific program at the German Marshall Fund of the United States. “That might ease some of the pressure that is rising internally.”

In part, Mr. Ma’s trip is another move in the contest between his Nationalist Party and Mr. Lai’s incoming administration.

Mr. Lai won 40 percent of the presidential vote, prevailing in a three-way race. But the Nationalists won the most seats in the legislative election. Both the Nationalists and Chinese officials have said that those results showed that Mr. Lai does not represent mainstream Taiwanese opinion, a message Beijing is likely to amplify during Mr. Ma’s visit.

But Mr. Ma’s visit to China has risks for his party. He represents a wing of the Nationalists committed to Taiwan’s reconciliation with Beijing as part of one Chinese nation, an idea that other sectors of his party, and Taiwanese voters, are wary of. In the final days of Taiwan’s presidential race, the Nationalist candidate, Hou Yu-ih, distanced himself from Mr. Ma over comments that the former president made about Taiwan’s military vulnerabilities.

“No matter how much you defend yourself, you can never fight a war with the mainland; you can never win,” Mr. Ma told Deutsche Welle. Unification with China could be acceptable to Taiwan, he added, if achieved peacefully and democratically.

According to a poll of Taiwanese people by the Election Study Center of National Chengchi University in Taipei, about 1 percent support unification “as soon as possible.” Nearly 90 percent favor some version of Taiwan’s current ambiguous status quo: self-ruling, separate from China, but short of full formal independence.

The D.P.P. has accused Mr. Ma of selling out Taiwanese interests by going to China.

“The Chinese Communists are trying to use Ma Ying-jeou’s visit to frame the terms for political discussion on both sides of the Taiwan Strait,” Wang Ting-yu, a Democratic Progressive lawmaker, said in an interview. Mr. Ma does not represent mainstream views within his own party, Mr. Wang said: “He has lost the mandate of public opinion.”

As president, Mr. Ma expanded economic ties with China, including tourism. But his plans for a more ambitious trade pact ran aground in 2014 after protesters occupied Taiwan’s legislature, arguing that the agreement would undermine Taiwan’s economic autonomy.

Mr. Ma first visited China last year, though he did not meet with Mr. Xi. This time, he will lead a group of Taiwanese students to Guangdong Province in southern China and to Shaanxi Province in the northwest, there to attend a ceremony honoring the Yellow Emperor, the mythic forefather of Han people. Finally, they will visit Beijing, where the meeting with Mr. Xi may take place.

Taiwan’s Nationalist Party issued a statement defending Mr. Ma’s trip and expressing “hope that this visit will contribute to cross-strait peace and stability.” It also noted that Mr. Ma no longer held any senior posts in the party.

“They are setting up some protection,” said Dennis Lu-Chung Weng, an associate professor at Sam Houston State University in Texas who studies Taiwanese politics. “If anything goes wrong in Beijing, or Ma Ying-jeou mentions something unacceptable to the Taiwanese people, the party will indicate that they are not with Ma Ying-jeou on that.”