President Barack Obama won't back off demands that Japan ease barriers for U.S. automakers before joining negotiations for a regional Pacific trade agreement when he meets Friday in Washington with Prime Minister Shinzo Abe, White House aides said.

A more open market for companies such as Ford Motor Co., General Motors Co. and Chrysler Group LLC remains "an important precondition" to Japan's potential entry into the proposed trade pact known as the Trans-Pacific Partnership, said Mike Froman, Obama's deputy national security adviser for international economic affairs.

The partnership "is intended to be a comprehensive, ambitious, high-standard, 21st-century trade agreement," Froman said on a conference call with reporters. "And anybody who joins the TPP would be expected to sign on to that goal."