The government upheld plans Thursday to require travelers from Canada, Mexico and other allied nations to show a passport (search) or other secure document to enter the country.

The departments of State and Homeland Security said they expect to officially adopt the new policy — which drew complaints from travelers, the effected nations and even President Bush — by the end of the year. But they pushed back by a year the date when the requirements would begin to effect travelers.

Department officials also said they will keep working to come up with a cheaper, more widely used alternative document to allow U.S. citizens and other travelers to cross into the country over land borders (search).

Under the new timeline, all who travel by air or sea from Canada, Mexico, the Caribbean, Bermuda and South and Central America will have to show a passport or one of four other secure documents by Dec. 31, 2006.

Only an estimated 7 million people living on either side of the Canadian and Mexican borders currently hold the other types of documents that allow frequent travel across the borders. Only about 60 million U.S. citizens — about 20 percent of the population — have passports.

Travelers crossing land borders, namely from Mexico and Canada, will have to comply with the rules by Dec. 31, 2007.

After the rule was announced in April, Bush said he was "surprised" by the passport requirement, which drew sharp criticism from the Canadian government, and said he had ordered a review of the plans.