President Biden on Saturday brushed off noisy statements issued by both sides in the debt and spending talks gripping Washington, dismissing them as little more than the posturing typical of any negotiation and expressing confidence that he will still be able to strike a deal with Republicans to raise the debt ceiling.

Speaking on the sidelines of a summit meeting in Hiroshima, Japan, Mr. Biden told reporters that he was not worried about the debt talks back home. “Not at all,” he said. He later added, “I still believe we’ll be able to avoid a default and get something decent done.”

Mr. Biden’s comments came after a tumultuous day of thrust and parry carried out across the oceans. Speaker Kevin McCarthy on Friday abruptly declared a “pause” in talks aimed at raising the debt ceiling to avoid a national default while adopting ways to reduce the deficit, only to send his negotiators back to the table later in the day. But that session broke up after only an hour, and the White House then released a blistering statement accusing Republicans of sticking to “extreme MAGA priorities.”

The president essentially called all of that just theater that no one should take too seriously. “It goes in stages,” he told reporters during a meeting with Australia’s prime minister. “And what happens is the first meetings weren’t all that progressive, the second ones were, the third one was, and then what happens is the carriers” — meaning the negotiators — “go back to principals and say this is what we’re thinking about and then people put down new claims.”

Noting that he has been through many such negotiations in his half-century in Washington, he made clear that he believed such positioning was little more than for show — presumably including the statement his own staff had issued barely an hour earlier. Each side, he indicated, needs to take a firm stand in order to extract the best deal for itself. That, he added, did not mean they could not eventually get to a consensus.

Mr. Biden’s public confidence in the prospects for a deal has stirred discontent among some liberals who fear he will give away too much to Mr. McCarthy’s Republicans, including work requirements for recipients of aid to the indigent. As it is, the president has essentially dropped his insistence that he would not negotiate spending constraints as part of an agreement to raise the debt ceiling; the White House maintains that the spending talks now underway are theoretically separate from the issue of raising the debt ceiling, a characterization few others accept.

For days, Mr. Biden and aides traveling with him in Japan have expressed optimism that they could work out a deal by the time the president returned to Washington on Sunday or shortly thereafter, in plenty of time to raise the debt ceiling before the nation would otherwise reach a default as early as June 1. The White House has essentially cleared the president’s schedule for next week, presumably to allow for further talks.

But his comments to reporters on Saturday left a mixed set of messages in just a matter of hours. The White House started the day in Japan with a briefing by Karine Jean-Pierre, the press secretary, who offered a more measured assessment of the talks than the positive tone of recent days, saying that a deal would depend on whether Mr. McCarthy “will negotiate in good faith” and that everyone should recognize that “you don’t get everything you want.”

She emphasized that “we need Republicans and Democrats,” alluding to the concern that congressional Democrats could bolt from an eventual deal if they perceive that the president has gone too far. But she denied that the White House was more pessimistic, using the word “optimistic” 14 times during her briefing.

Three hours later, after Mr. Biden spoke with his negotiators back in Washington, his communications director, Ben LaBolt, issued a much different statement that never used the word “optimistic.”

“Republicans are taking the economy hostage and pushing us to the brink of default, which could cost millions of jobs and tip the country into recession after two years of steady job and wage growth,” Mr. LaBolt said.

“Republicans,” he added, “are recycling a barely watered down version of their extreme budget proposal” that would result in spending cuts on education, law enforcement and health care, while reversing plans to hire more I.R.S. agents to target tax cheats and extending tax breaks passed under President Donald J. Trump. He added that any agreement should include tax increases on the wealthy and corporations, not just spending cuts.

“There remains a path forward to arrive at a reasonable bipartisan agreement if Republicans come back to the table to negotiate in good faith,” Mr. LaBolt said. “But President Biden will not accept a wish list of extreme MAGA priorities that would punish the middle class and neediest Americans and set our economic progress back.”

The federal government reached its $31.4 trillion debt ceiling set by law months ago. The Treasury Department has been employing a set of accounting maneuvers to avoid breaching it but has said it could run out of options as early as June 1, which would throw the nation into default for the first time as it failed to pay its obligations, unless Congress and the president came to an agreement.