Taiwanese President Chen Shui-bian has repeated his suggestion that guidelines on unification with China be scrapped, despite Washington's reservations.
Mr Chen told Mr Simmons that the guidelines were 'absurd'
Mr Chen told a visiting US Congressman that the National Unification Council and its National Unification Guidelines were anachronistic.
When the Taiwanese leader first made such remarks, Beijing called him a "troublemaker and saboteur".
China suspects the move confirms Mr Chen is pushing for independence.
The guidelines were "absurd products of an absurd era", Mr Chen told Connecticut Republican Robert Simmons on Wednesday.
"It deprives Taiwan people's rights to freely decide on cross-Strait relations and the future direction of our country," he said.
China sees Taiwan as its territory, threatening to use force if the island moves towards formal independence.
The US, Taiwan's closest ally in the face of this threat, has said it supports the status quo.
The National Unification Council was set up in 1990 as an attempt to convince the Chinese authorities that Taiwan was committed to reunification, and it helped kick-start landmark talks between the two sides in the early 1990s.
Mr Chen's independence-leaning Democratic Progressive Party (DPP) has always opposed the Council, but Mr Chen promised when he first took office in 2000 that he would not scrap it or its guidelines.