Taiwan's opposition leader said Thursday if he wins office he will boost military spending and show "self-confidence" towards a rising China, as he courted US support during a visit to Washington.

Su Tseng-chang, chairman of the Democratic Progressive Party, said that he generally welcomed the relationship between Taiwan and China that has grown since the island elected Beijing-friendly President Ma Ying-jeou in 2008.

But Su charged that China has not reciprocated goodwill gestures from Taiwan and said that any efforts by the mainland to change the island's identity as self-governing and democratic were "totally unacceptable."

"Taiwan should engage a rising China with self-confidence," Su told the Brookings Institution think tank.

He said that, if the opposition takes power, "Taiwan will continue this friendly approach toward the People's Republic of China, but we also urge the PRC not to push Taiwan into a corner."

Ma, who spearheaded a landmark trade agreement with the mainland, cruised to a second term last year. The opposition is hoping to regain momentum in local races ahead of the next presidential election in 2016.

Su, who plans to open an office for the party in Washington, said he was telling US policymakers that his party was "fully committed to Taiwan's self-defense" at a time when China is rapidly increasing its military budget.

"Democracy and security do not fall from heaven. They come with a cost," he said. "It is time for us to demonstrate that we are serious about our own self-defense."

"We ask not what the US can do for Taiwan, but ask what Taiwan can do to earn the US support," he said.

The United States is obligated by domestic law to provide Taiwan with the means of self-defense.

President Barack Obama's administration has approved more than $12 billion in sales and equipment upgrades but held off on Taiwan's requests to buy state-of-the-art F-16 jets, a step against which China has repeatedly warned.

Ma has set a target of devoting three percent of Taiwan's gross domestic product to defense but the government has instead pruned the budget as other economic priorities emerge and tensions with China decrease.

Taiwan's government was founded by the nationalist Kuomintang, now led by Ma, in 1949 after it lost the mainland's civil war. The island has since developed into a vibrant democracy.

Beijing considers Taiwan part of its territory awaiting reunification, by force if necessary.

The Democratic Progressive Party flirted with independence while in power from 2000 to 2008 under president Chen Shui-bian, who infuriated China through moves such as abolishing a largely symbolic office on reunification.

"Taiwan is a sovereign country, with its national title the Republic of China," Su said, calling the stance a "core value" of the party.

But Su said that his party's policy on China "will not focus entirely on domestic politics" and said he hoped on the international stage "to reassure our good friends that we will not make any sort of surprise move."

Both Taiwan's government and the opposition have put a major priority on cultivating relations with the US Congress. Leading lawmakers welcomed Su at a reception inside the Capitol on Wednesday.

Representative Steve Chabot, who heads the House Foreign Affairs subcommittee on East Asia, called on Taiwan to release from prison former president Chen, who earlier this month attempted to hang himself with a towel.

"There is no further good to be served by having him behind bars," said Chabot, a Republican from Ohio.

Chen was sentenced to life in prison on corruption charges a year after leaving office. The sentence was later reduced to 20 years.