[Updated 5:11 p.m.] President Obama's appearance and comments at an immigration rally was followed by comments from Gustavo Torres, executive director of the Baltimore-based immigrant advocacy group CASA de Maryland.

Torres told the crowd, "Mr. President, we are going to hold you accountable" after Obama said he would do everything he could to reach a deal on immigration.

[Updated 4:21 p.m.] Speaking by video to the crowd at an immigration rally, President Barack Obama said he would do "everything in my power" to get a bipartisan deal within the year.

"You know as well as I do that this won't be easy, and it won't happen overnight," Obama said. "But if we work together across ethnic, state and party lines, we can build a future worthy of our history as a nation of immigrants and a nation of laws."

[Posted at 3:45 p.m.] Tens of thousands of people turned out on Washington's National Mall on Sunday to support the Obama administration in its next big battle, a renewed effort to overhaul U.S. immigration laws.

"You are a spectacular sight," Ali Noorani, chairman of the coalition that organized the demonstration, told the crowd. Noorani said the rally had drawn more than 150,000 people "from across the country, and we are demanding comprehensive immigration reform now."

Noorani's figure could not be verified immediately, but the crowd packed more than two blocks of the Mall between the Capitol and the Washington Monument.

Though overshadowed by the historic debate on health care taking place in the nearby halls of Congress, Sunday's rally set the stage for a revival of efforts to reshape U.S. immigration law. The issue has been largely sidelined since 2007, when the Bush administration's push to establish a path to legal citizenship for the estimated 11 million people in the United States illegally foundered in Congress.

The rally followed last week's publication of a new plan backed by Sen. Charles Schumer, D-New York, and Sen. Lindsey Graham, R-South Carolina. The plan would create a "tough but fair" path to legalization, as well as a temporary worker program and tighter border controls, the sponsors wrote in a Washington Post opinion piece Friday.

President Barack Obama, who was scheduled to address the rally via video, called the senators' plans "promising," and said it "should be the basis for moving forward." He called on Congress to act on that plan "at the earliest possible opportunity."

Obama's push on immigration also helped secure a key vote for his health-care bill. Rep. Luis Gutierrez, D-Illinois, announced his support for the bill after receiving a commitment to move forward on immigration "as soon as possible."

"The wait is over. The time is now," Gutierrez told Sunday's rally. "We're ready to turn our hope into victory."