The Obama administration has met many of the border security benchmarks Congress set in 2007 as a prerequisite to immigration reform and now it's time to change the law, Homeland Security Secretary Janet Napolitano said Friday.

Napolitano, designated by President Obama to lead the administration's immigration reform efforts, said many members of Congress had said they could support immigration reform, but only after border security improved, Napolitano said.

"Fast forward to today, and many of the benchmarks these members of Congress set in 2007 have been met," she said in a speech to the Center for American Progress, a liberal think tank.

She cited construction of 600 miles of border fence and the hiring of more than 20,000 Border Patrol agents. Illegal immigration has also fallen sharply because of better enforcement and the economy.

"I've been dealing hands-on with immigration issues since 1993, so trust me: I know a major shift when I see one, and what I have seen makes reform far more attainable this time around," Napolitano said.

Congress passed tough immigration enforcement legislation in 2006 that called for building 700 miles of border fences and barriers. Immigration critics have said the fence has not been built with double layers as the law required and is not all fencing.

"How can they claim that enforcement is 'done' when there are more than 400 open miles of border with Mexico, hundreds of thousands of criminal and fugitive aliens and millions of illegal immigrants taking American jobs?" said Rep. Lamar Smith of Texas, the top Republican on a House immigration subcommittee.

Napolitano said the immigration and border security improvements are not enough. "The laws themselves need to be reformed," she said.

Obama has repeatedly said immigration reform is a priority, although it has been pushed further down the list as he has taken on the economy and health care reform.

Sen. Charles Schumer, D-N.Y., has said he would introduce legislation by early next year. New Jersey Sen. Bob Menendez, who heads the Senate Democrats' campaign arm, has said immigration reform must be done by March or it won't be taken up until after the 2010 elections.