Congress has had “the most productive post-election period that we’ve had in decades,” President Barack Obama said Wednesday afternoon, declaring that the lame-duck session has been a “season of progress for the American people.”

Obama hailed Wednesday’s ratification of the new Strategic Arms Reduction Treaty with Russia, which he called his “top national security priority,” as well as the completion on Saturday of a repeal on the military’s ban on openly gay service members and this month’s temporary extension of the 2001 and 2003 tax breaks.

Each milestone was achieved with support from some Republicans, which Obama said proves “we are not doomed to endless gridlock.” He spoke at a last-minute news conference held a few hours before his planned evening departure for a family vacation in Hawaii. The first lady and their daughters left for Hawaii earlier in the week. Obama’s annual holiday trip was also delayed last year, when the president waited in Washington for the Senate to vote on a health care overhaul on Christmas Eve.

The assistance from some Republicans on key bills must be “a recognition on their part that people are going to be paying attention to what they’re doing,” in addition to watching the actions of Democrats and the administration, the president said.

“We’ve shown in the wake of the November elections that we have the capacity” to work together, Obama said. “My hope heading into the new year is that we can continue to heed the message of the American people and hold to a common purpose.”

During the victory lap news conference, the president hailed accomplishments on major legislation in the lame-duck session and over the course of the 111th Congress, which he called one of the “most productive in generations.”

Obama said his administration got the message from Election Day, when Democrats lost dozens of Congressional seats in what he dubbed a “shellacking.” He said he understands Americans believe “it’s time to find common ground on challenges facing our country” and said it’s a message “I will take to heart” in the new year. The president said the administration and Congress will “pivot” to focus on jobs and growth in 2011.

Obama also noted that he is “very disappointed” the Senate did not pass the DREAM Act, an immigration measure offering illegal immigrant children a pathway to citizenship. He promised he would try again in the new Congress, saying, “I am persistent. If I believe in something strongly, I stay on it.”

He said he expects a “robust debate” on the budget in the coming year and noted the failure of Congress to fund the government over the long term. The conversation must be about cutting spending “while still making investments that we do need,” he said.

“Regardless of how the politics play out in 2012, the people will be better for it,” Obama said.

The president also lauded Sen. Dick Lugar (R-Ind.) for helping to win support for the nuclear weapons treaty with Russia, and he told reporters that he had phoned Lugar following the vote. Obama said he reminded Lugar that his first trip as a Senator was with the Indiana Republican and focused on nuclear weapons, a foreign policy issue that Obama wrote about in his book, “The Audacity of Hope,” and spoke about frequently on the presidential campaign trail. Lugar’s strong working relationship with the White House has been central to conservative criticism that could materialize in a GOP primary challenge in 2012.