With his far-reaching inaugural address Monday, an emboldened President Barack Obama made the case for an activist federal government and a decidedly liberal agenda while challenging the gridlocked Congress to act.

In a surprisingly aggressive address that called for action on climate change, gay rights, immigration and the nation’s partisan divide, Obama urged the country to come together to reaffirm — and extend — its founding principles.

“Being true to our founding documents does not require us to agree on every contour of life,” Obama said. “It does not mean we all define liberty in exactly the same way or follow the same precise path to happiness. Progress does not compel us to settle centuries-long debates about the role of government for all time, but it does require us to act in our time.”

The bold push for long-sought liberal policy goals came against the backdrop of a Congress that may not even be able to avoid a government shutdown in March and has only managed to govern through serial self-imposed deadlines and crises.

But the president went well beyond the cautious, compromise-first efforts in his first term that so often disappointed his liberal base, suggesting that he will keep to the harder-nosed negotiating style he has employed since Election Day.

Liberals cheered, believing the president was making the argument they always thought he should make.

“It wasn’t compromising at all. It laid out the things that need to be done and asked us to historically think about the people who met these challenges before,” Rep. George Miller, D-Calif., said. “I’ve been waiting a long time for this speech.”

Miller said Obama four years ago clearly felt the burden of the financial crisis he inherited. But with the economy making modest gains, he can think bolder. “Is this American rainbow all going to be included?” he asked.

Rep. Henry Waxman praised Obama’s climate change push, telling the president after the speech that he needs to do more.

“I think the president is determined to move forward on a lot of issues that he couldn’t deal with in his first term, and particularly the first one he mentioned was climate change and global warming. I’m delighted he did,” the California Democrat said.

While many Republicans had only lukewarm comments about the speech — with some grousing at the tone and the activist agenda — many Democrats believe Obama’s speech will force the GOP to respond.

Rep. Debbie Wasserman Shultz, the chairwoman of the Democratic National Committee, said the point isn’t necessarily what might seem achievable in Congress right now.

“The point is, when a president gives an inaugural address, he should and did lay out what requires our attention,” she said.

The president made the case that the nation needs to come together to do things people cannot do on their own — from training teachers to building roads to providing for the nation’s defense.

The president made special mention of the civil rights struggles that helped lead to his becoming the first African-American president. He tied that struggle — and the coincidental fact that the inaugural ceremony was being held on Martin Luther King Jr. Day — to new battles for civil rights, including gay rights, immigration, and pay equity for women.

“Our journey is not complete until our gay brothers and sisters are treated like anyone else under the law — for if we are truly created equal, then surely the love we commit to one another must be equal as well,” Obama said. He added: “Our journey is not complete until we find a better way to welcome the striving, hopeful immigrants who still see America as a land of opportunity; until bright young students and engineers are enlisted in our workforce rather than expelled from our country.”

In a nod to his gun control agenda, the president mentioned the Dec. 14 Newtown, Conn., massacre and said the country must make sure that children in urban, suburban and inner cities “know that they are cared for and cherished and always safe from harm.”

On the deficit fights that have swallowed much of the past two years, the president called for reform that still preserves entitlement programs.

“The commitments we make to each other — through Medicare and Medicaid and Social Security — these things do not sap our initiative; they strengthen us. They do not make us a nation of takers; they free us to take the risks that make this country great.”

The mention of “takers” came from Obama’s 2012 campaign against GOP nominee Mitt Romney, whose campaign lost momentum when a tape surfaced of him referring to the “47 percent” of Americans who don’t pay income tax. The reference was one of many moments when the president challenged his political opponents to soften their resistance compromising with him.

“We cannot mistake absolutism for principle or substitute spectacle for politics or treat name-calling as reasoned debate. We must act, knowing that our work will be imperfect,” he said. “We must act, knowing that today’s victories will be only partial.”