with congressional Republicans and his top presidential rivals, Mitt Romney and Newt Gingrich.
"Anyone who tells you America is in decline or that our influence has waned, doesn't know what they're talking about," Obama said — a clear response to the White House hopefuls who have pummeled him for months.
In an attack on the nation's growing income gap, Obama called for a new minimum tax rate of at least 30 percent on anyone making more than $1 million. Many millionaires — including Romney — pay a rate less than that because they get most of their income from investments, which are taxed at a lower rate.
"Now you can call this class warfare all you want," Obama said. "But asking a billionaire to pay at least as much as his secretary in taxes? Most Americans would call that common sense."
Obama calls this the "Buffett rule," named for billionaire Warren Buffett, who has said it's unfair that his secretary pays a higher tax rate than he does. Emphasizing the point, Buffett's secretary, Debbie Bosanek, attended the address in first lady Michelle Obama's box.
Obama made his appeal on the same day that Romney released some of his tax returns, showing he made more than $20 million in a single year and paid around 14 percent in taxes, largely because his wealth came from investments.
In advance of Obama's speech, Romney said, "Tonight will mark another chapter in the misguided policies of the last three years — and the failed leadership of one man."
Obama highlighted his national security successes — the raid that killed Osama bin Laden, the diminished strength of al-Qaida and the demise of Moammar Gadhafi. In hailing the men and women of the military, the commander in chief contrasted their cooperation and dedication with the divisions and acrimony in Washington.
"At a time when too many of our institutions have let us down, they exceed all expectations," Obama said. "They're not consumed with personal ambition. They don't obsess over their differences. They focus on the mission at hand. They work together. Imagine what we could accomplish if we followed their example."
Obama leaves Washington for a three-day tour of five states crucial to his re-election bid. On Wednesday he'll visit Iowa and Arizona to promote ideas to boost American manufacturing; on Thursday in Nevada and Colorado he'll discuss energy; and in Michigan on Friday he'll talk about college affordability, education and training.
He also addresses a conference of House Democrats focused on their own re-election in Cambridge, Md., on Friday.
Polling shows Americans are divided about Obama's overall job performance but unsatisfied with his handling of the economy.
Biden was interviewed on ABC's "Good Morning America," NBC's "Today" show and "CBS This Morning." Cantor appeared on CBS and MSNBC.