WASHINGTON — Lawmakers in Congress from both political parties have accused the Trump administration of delaying an $8 billion sale of F-16 fighter jets to Taiwan, the self-governing democratic island off the coast of China that is supported by the United States.

Chinese officials have said they object strongly to the sale of 66 jets requested by Taiwan, which would be by far the largest such purchase by its government in many years. Lawmakers are now questioning whether the Trump administration is delaying approval of the sale, either to avoid upsetting Beijing while delicate trade negotiations are underway or to use it as a bargaining chip.

Any such move by the administration would ignite intense bipartisan opposition in Congress.

“Our support for Taiwan through arms transfers is not up for negotiation with Beijing,” Representative Michael McCaul of Texas, the top Republican on the House Foreign Affairs Committee, told The New York Times on Monday.

“I will support the sale of F-16s to Taiwan as soon as the State Department notices them to our committee, which I expect to happen soon,” Mr. McCaul said.