President Biden on Wednesday said he expected President Vladimir Putin of Russia would invade Ukraine, delivering a grim assessment of the ability of the United States and its European allies to persuade the Russian leader not to send troops across the border.

“Do I think he’ll test the West, test the United States and NATO, as significantly as he can? Yes, I think he will,” Mr. Biden told reporters during a near two-hour news conference in the East Room of the White House, adding: “But I think he will pay a serious, and dear price for it that he doesn’t think now will cost him what it’s going to cost him. And I think he will regret having done it.”

Asked to clarify whether he was accepting that an invasion is coming, Mr. Biden said: “My guess is he will move in. He has to do something.”

The president’s comments came as Russia has marshaled more than 100,000 troops to the border with Ukraine over the past several months. Mr. Biden has vowed extensive sanctions if an invasion happens, but he suggested that they would not be enough to keep Mr. Putin from moving forward with military action.

“I probably shouldn’t go any further. But I think it will hurt him badly,” he said.

Later, Mr. Biden offered less certainty, saying that he was not sure whether Mr. Putin had made up his mind on invading.

“I suspect it matters which side of the bed he gets up on in the morning as to exactly what he’s going to do,” Mr. Biden said.

Earlier in the news conference, Mr. Biden accused Republicans of refusing to get “in the game” on governing the country and insisted that he did not over promise to the American people despite his failure to pass wide-ranging social spending legislation or voting right protections.

“I did not anticipate that there would be such a stalwart effort to make sure that the most important thing was that President Biden didn’t get anything done,” he said.

“What are Republicans for?” he asked in response to a question about his stalled agenda. “What are they for? Name me one thing that they are for.”

Mr. Biden did not mention that much of his agenda has been blocked by Democratic lawmakers, not Republicans. And he insisted that he would not pare back his ambitions in the face of difficult odds in Congress.

“We just have to make the case what we’re for and what the other team’s not,” he said.

Mr. Biden’s comments came as he faced reporters in a formal news conference for only the second time in his presidency and less than a day before the first anniversary of his inauguration amid a stalled agenda and low approval ratings.

In that year, Mr. Biden succeeded early in passing a $1.9 trillion economic stimulus bill, getting millions of Americans vaccinated, and negotiating a bipartisan bill to invest $1 trillion in the nation’s roads, bridges, pipes and broadband.

But the president had a series of failures since the summer, including a rushed and chaotic exit from Afghanistan, a monthslong battle with two Democratic senators over his far-reaching social spending legislation, and the inability to pass voting rights protections he describes as crucial to the fate of democracy in the country.

Mr. Biden was defensive about his legislative failures, saying that he intended to continue to press for passage of his social policy legislation.

“It’s clear to me that we’re going to have to probably break it up,” he said, suggesting that parts of the $2.2 trillion bill passed by the House would be able to find support in the Senate. He did not say how he thought he could get Republicans to back those provisions.

The president has not yet succeeded in meeting his own goals for combating climate change. And while he has reversed some of President Donald J. Trump’s harsh immigration policies, he has not yet delivered on his broader promise for a pathway to citizenship for millions of undocumented Americans.

And on the central promise he made during the 2020 campaign — to “shut down” the pandemic that has upended school, work and social life in the country for two years — Mr. Biden has struggled to respond to the coronavirus variants that have killed more than 250,000 Americans since the summer.

The president defended his response to the pandemic, saying that his administration had succeeded in vaccinating nearly 75 percent of all adults. He said he wished he had “moved a month earlier” to ramp up testing capacity, but he said that was not a mark of incompetence given everything else his government had done to fight the virus.

“Am I satisfied with the way in which we have dealt with Covid and all the things that go along with it?” he said. “Yeah, I am satisfied. I think we’ve done remarkably well.”

He added: “Nobody has ever organized — nobody has ever organized — a strategic operation to get as many shots into arms by opening clinics and being able to get so many people vaccinated.”

The president took questions even as members of his party in the Senate delivered speeches on behalf of the voting rights legislation in what they already acknowledged was a doomed effort because of unified Republican opposition and refusal by a handful of Democratic senators to change the chamber’s rules.

The idea of the debate was to underscore Republican refusal to deal with what Democrats insist is election subversion and voter suppression in states across the country. But the vote also highlighted the limits on Mr. Biden’s ability to pressure members of his own party to fall in line behind their president.

Mr. Biden said that he had not yet completely given up on passing some kind of voting rights legislation, and he rejected criticism from some African Americans who say he had not fought hard enough for voting protections.

“I’ve had their back,” he said. “I’ve had their back my entire career, never not had their back. I started on the voting rights issues long, long ago.”