But the United States is on track to meet considerable challenges from the pandemic and inflation, Biden said, citing job growth, low unemployment and new business growth.
Asked whether he had promised more than he could deliver on the 2020 campaign trail, Biden was adamant: "I didn’t over-promise."
For 2022, Biden said he needed to leave the White House to talk to the American people more regularly.
"I'm gonna get out of this place more often. I don't get a chance to look people in the eye," he said, and "let them take a measure of who I am."
Biden faces a slump in opinion polls as his fellow Democrats gird for Nov 8 midterm elections in which their majorities in Congress are on the line. Two of Biden's top legislative priorities -- his signature economic and social spending package called Build Back Better and a federal voting rights bill -- have languished.
Biden said one challenge he underestimated going into the White House was the "stalwart" opposition of Republicans to his presidency, which he characterised as worse than it was when he was vice president under Barack Obama.
Republican Senate Minority Leader Mitch McConnell "has been clear, he’d do anything to prevent Biden from being a success," the president said, speaking about himself in the third person. "Name me one thing they're for," he said of the opposing party.
Republican National Committee Chairwoman Ronna McDaniel shot back that "Biden showed how deeply out of touch he is, claiming that the struggles Americans are facing each day aren't real."
Asked about surveys showing he lost favour among some voters who supported him in 2020, Biden said: "I don't believe the polls."
But he acknowledged that Build Back Better was all but dead in its old form. Instead, the president said, he expected that he could get "big chunks" of that bill passed, if not the full package.
Biden raised concerns that Republicans could succeed in undermining the legitimacy of the elections this year.
Biden's fellow Democrats are fighting to retain their control of Congress in the coming elections amid a flood of Republican-backed state laws that civil rights advocates say could suppress Black and other minority votes.
"The increase in the prospect of it being illegitimate is in direct proportion to us not being able to get these reforms passed," Biden said about federal voting rights law.
Biden has held nine total news conferences in his first year in office, including six solo, a slower pace than his most recent predecessors, according to the American Presidency Project at University of California, Santa Barbara.