WASHINGTON – Even as it bowed to complaints about vacation-ruining passport delays, the Bush administration insisted Friday it is pressing ahead with restrictions next year that could mean even bigger travel headaches.

Responding to protests, the State Department and the Homeland Security Department said they would temporarily relax a rule requiring passports for air travel to Canada, Mexico, Bermuda and the Caribbean.

From now until the end of September, they said, travelers would be allowed to fly to those destinations if they present government-issued identification, such as a driver’s license, and a receipt from a State Department Web site showing they had applied for a passport.

The reprieve applies only to those with applications pending, not those who apply in coming days for travel later this summer. Travelers with receipts but not passports should expect extra scrutiny.

The goal is to allow more time to process a flood of passport applications that came in since the rule, one of many enacted after the Sept. 11 terrorist attacks, took effect this year.

Despite that move, security officials said they would proceed, as of January, with a requirement that passports be presented at all U.S. sea and land border crossings. Homeland Security plans to offer a draft in two weeks that spells out how the new rule would be implemented, said a spokesman.

The application surge is the result of the Western Hemisphere Travel Initiative, in effect since January, which required U.S. citizens to use passports when entering the U.S. from Canada, Mexico and the Caribbean by air.