WASHINGTON — President Obama, seeking to put the prosperity and promise of the middle class at the heart of his second-term agenda, called on Congress on Tuesday night to raise the federal minimum wage to $9 an hour, saying that would lift millions out of poverty and energize the economy.

In an assertive State of the Union address that fleshed out the populist themes of his inauguration speech, Mr. Obama declared it was “our generation’s task” to “reignite the true engine of America’s economic growth — a rising, thriving middle class.”

“Every day,” he said, “we should ask ourselves three questions as a nation: How do we attract more jobs to our shores? How do we equip our people with the skills to get those jobs? And how do we make sure that hard work leads to a decent living?”

The increase in the minimum wage, from $7.25 an hour now, was the most tangible of a raft of initiatives laid out by the president, from education and energy to public works projects. Taken together, Mr. Obama said, these investments would accelerate the nation’s recovery by helping those in the broad middle class.