WASHINGTON – A driver’s license won’t be good enough to get you past a checkpoint at the Canadian border in two weeks, and the new rules will mean longer lines, the nation’s Homeland Security chief said Thursday.

That may be a surprise to some Americans trying to return home, but in an interview Chertoff bristled at criticism that such extra security would be inconvenient.

More than 800,000 people enter the U.S. through land and sea ports each day.

“It’s time to grow up and recognize that if we’re serious about this threat, we’ve got to take reasonable, measured, but nevertheless determined steps to getting better security,” he said.

Thousands of people enter the U.S. through land crossings every day. The biggest effect of the change will be at the Canadian border since it applies to both Canadians and Americans. Non-Americans coming in through Mexico already need extra documentation.

Under the new system, which takes effect Jan. 31, Americans and Canadians who are 19 or older will have to present proof of citizenship when they seek to enter the United States through a land or sea port of entry. A passport will be fine, or a birth certificate coupled with some other ID, such as a driver’s license.

Chertoff said he had been surprised to learn that simply stating “I am an American” and showing an ID card has been sufficient to get back into the country. “I don’t think in this day and age we can afford the honor system for entering the United States,” he said. “Regrettably, we live in a world in which people lie sometimes about their identity.”

For people other than Americans or Canadians, the rules at the northern border will be unchanged – passports and visas will still be required. The same goes for non-Americans at the Mexican border.

Chertoff said longer lines at the border in the early days of the new policy are inevitable. “Until people get the message, there will be some delays,” he said.

He predicted that would change once people got used to the new system, and he said border agents would be flexible in applying the new rules at the beginning.

Not moving to the new restrictions would be a tragic mistake, Chertoff said. “I can guarantee if we don’t make this change, eventually there will come a time when someone will come across the border exploiting the vulnerabilities in the system and some bad stuff will happen. And then there’ll be another 9-11 commission and we’ll have people come saying, ‘Why didn’t we do this?”‘

More than 8,000 different documents have been used to enter the United States, in some cases even library cards. The proof-of-citizenship requirement will greatly reduce the ability to sneak past border agents with fake papers, Chertoff said. Border agents will now accept about two dozen types of ID.

Chertoff complained as recently as a year ago that checking birth certificates placed an “enormous burden” on agents because such documents come from thousands of jurisdictions and are hard to verify.

Congressional critics representing northern border states were anything but impressed with Chertoff’s rhetoric.

Sen. Susan Collins, R-Maine, said in a news release that she spoke Thursday with Chertoff “to express my concerns about the new requirements for documents” at the border. She said she had urged him to reconsider them.

“While I understand that the secretary views this initiative as separate from the requirement for a passport that the Congress has prohibited him from implementing until June of 2009, the clear message we were sending to the department was to be more attuned to the legitimate travel and commerce of border community residents,” Collins’ statement said. “I reminded Secretary Chertoff that the department had caused unacceptable delays at the border crossings last year when it implemented license checks without having the necessary staff in place.”

Collins is seeking re-election this year. Democratic Rep. Tom Allen, who represents Maine’s 1st Congressional District, including Knox County, is seeking the Democratic nomination to challenge Collins. In a statement Thursday, Allen said Chertoff’s decision to implement documentation requirements “before required by law clearly violates explicit direction from Congress. I will join effort with others in Congress to ensure that [the department’s] actions do not harm our border economy or excessively burden Maine citizens.

Vermont Sen. Patrick Leahy, Democratic chairman of the Senate Judiciary Committee, said the move does nothing to enhance security and will only hurt the economy. “When it comes to the northern border, the muddled thinking and poor planning at [Homeland Security] seems to have no bounds, and the agency that botched Katrina seems to have no shame and no memory to boot,” Leahy said.

The Bush administration envisions an eventual passport requirement for everyone crossing the border into the United States. Congress passed a travel requirements law in 2004 but is having second thoughts, particularly as northern-state lawmakers argue the passport requirement will hurt tourism and trade.

The law’s requirements for air travelers in 2007 were followed by a massive backlog in passport applications, and some fear that will happen again this year as Homeland Security tries to go forward with the changes for land and sea crossings.

Also beginning in February, people can apply for a passport card that will be smaller than a regular passport but will include security features.

The 2004 law, passed in reaction to the Sept. 11 attacks, is called the Western Hemisphere Travel Initiative, designed to “get control” of the borders by verifying the citizenship and identity of everyone entering the U.S. by land, sea or air from Canada, Mexico and the Caribbean.

In June, Chertoff delayed the law’s passport requirement for land and sea crossings until next summer. Congress has since pushed it back even further to June 2009, and Chertoff has been forced to settle for birth certificates combined with other forms of ID as proof of citizenship.