“We think that the government is too soft and we want to show what we think,” said Zhang Xin, one of the many thousands of protesters who converged on the Japanese embassy in Beijing over recent days to vent their rage.

He and tens of thousands of other patriotic demonstrators nation-wide have condemned Japan for buying a cluster of disputed islands in the East China Sea - an outpouring of patriotism that would have been both assuring and alarming to Chinese Communist Party leaders viewing videos and reports of the protests in their leafy, walled compound in central Beijing.

Assuring because the crowds so fervently embraced Beijing’s message that it had a rightful claim over the islands, which Tokyo calls the Senkaku and Beijing calls the Diaoyu. Alarming because so many protesters were prepared to say publicly that they did not think their country’s leaders had the strength to act on that claim.

“China should make its own demands as a great power,” said Zhang, a 25-year-old wholesale food distributor. “I feel disappointed in the government. It’s not democratic enough and doesn’t heed our voice.

“I hope our leaders can catch up. There’s no conflict between democracy and patriotism.”

Many demonstrators held up portraits of Mao Zedong, the late Communist revolutionary leader who still serves as a default icon of unity and resolve in times of international tension.

But many protesters also invoked Mao as a sly rebuke to China’s current rulers, including President Hu Jintao, who have not made any public statements about the crisis since Japan bought three of the five disputed islands from a private owner last week, triggering condemnation from Beijing.

“Mao was new China’s first leader and he knew how to be tough on foreigners,” said Shi Lei, 25, a seafood salesman from China’s northeast. “If he were still alive we would be at war by now. Hu Jintao and those people are useless and impotent before Japan’s provocations.”

“Mao is our hero because he fought the Japanese and won,” said Chi Lixin, a 29-year-old Beijing businessman. “Our leaders today talk only of peaceful diplomacy and look what happened. They are giving away our land.”

That mixture of nationalism and frustration was echoed by many in the crowds in Beijing, Shanghai, Guangzhou and other Chinese cities. Thousands of police and anti-riot troops are sure to prevent that frustration turning into protests against the government, and by Wednesday police were bundling away would-be demonstrators at the Japanese embassy in Beijing.

“Of course, there truly are problems with Japan, but at the same time the government has used this to bundle up a domestic discontent and export it to Japan,” said Li Weidong, a political commentator and former magazine editor in Beijing.

“But it’s trying to calibrate that venting. The government doesn’t want to let this get out control.”

The risks to Xi and other emerging leaders are longer term than street protests, said experts on Chinese politics.

The Chinese government is preoccupied with the leadership succession that will happen at a Communist Party congress set to open as early as next month. No firm date has been set.

That succession has been jolted by scandals and uncertainties, and the government is navigating the economy through an unexpectedly sharp slowdown in growth.

The breakdown of relations with Japan will add to that brew of uncertainties, and yet pent-up public demands for a tough response from China will make it harder for Beijing to settle for compromise without appearing weak at home.

“Certainly nobody wants to be viewed as soft on Japan,” said Susan Shirk, a professor of China and regional relations at the University of California, San Diego.

Even if risks of military confrontation between Asia’s two biggest economies remain scant, room for China to engage in diplomatic give-and-take has shrunk, narrowing the options for any early exit from the territorial dispute.

“Everybody is competing for promotion and having a reputation for being soft on Japan would be definitely bad for your prospects,” said Shirk, who was a Deputy Assistant Secretary of State during the Clinton administration.

Chinese experts on Japan see rough times ahead.

“We have entered a new stage. In the past, the Chinese government advocated setting aside the island dispute and developing bilateral relations,” said Liu Jiangyong, a professor of international relations at Tsinghua University in Beijing.

“That period of history is over. We’re in a new phase of history, and that was a totally inevitable outcome of Japan purchasing the islands,” said Liu, who has advised Beijing.

For Xi, this new phase could be especially troublesome. He is virtually certain to succeed Hu Jintao as Communist chief this year and as president at a parliament session in March.

Like any new Chinese leader, Xi must try to establish his authority even while his predecessors retain considerable influence. In addition, there are widespread expectations that he will be more assertive and nimble than Hu, including abroad.

Chinese analysts and Western diplomats have said Xi is not the hardline, militarist nationalist of some portrayals. But activists campaigning for China to regain control of the disputed East China Sea islands said Xi would have to be more assertive than Hu in pressing Japan, or risk losing credibility.

Tong Zeng, president of the China Federation for Defending the Diaoyu Islands, cited a speech Xi gave in July.

In that speech at Beijing’s elite Tsinghua University, Xi said China would “protect relations with nearby countries and broader regional stability, on the basis of staunchly defending its national sovereignty, security and territorial integrity”, the Xinhua news agency reported at the time.

For Tong, the activist, that was a signal of a tougher line on the East China Sea islands and other territorial disputes.

“I believe that after he gets into office, the government will have a new policy on these issues,” Tong said in an interview before the latest protests.

“Public opinion is overwhelmingly in favour of defending the Diaoyu islands, and so I think the government will have to intensify its efforts.”