The Labor Department’s report on Friday that the economy added 559,000 jobs in May, an increase from April, boosted Democrats and the Biden administration, adding new fuel to the president’s claims that vaccinations and his economic program are starting to get the economy back on track after a halting recovery from the pandemic recession.

In remarks from Rehoboth Beach, Del., Mr. Biden said, “This is historic progress.” “Progress that is pulling our economy out of the worst crisis in a century.” He went on to credit that progress to his administration’s campaign to increase vaccine production and distribution in the United States, as well as the $1.9 trillion economic aid legislation he signed into law in March.

“None of this success is by chance. It isn’t by chance,” Mr. Biden said, praising “the American people’s cooperation in responding to my effort to get COVID under control, initially by wearing masks and getting vaccinated.”

However, the report, which fell short of analyst expectations for the second month in a row and revealed a slight contraction in the labor force, provided fodder for Republican critics of the president. They claim that increased unemployment benefits, which were extended by Mr. Biden’s aid legislation in March, are discouraging workers from returning to work and stifling what could be a faster recovery.

“Long-term unemployment is higher than when the pandemic began, and labor force participation resembles the stagnant 1970s,” said Representative Kevin Brady, the top Republican on the Ways and Means Committee. “It is past time for President Biden to abandon his assault on American jobs, tax increases, anti-growth regulations, and obsession with more emergency spending and endless government checks.” After the April report fell far short of expectations, Republican governors across the country moved to end the $300-per-week supplemental unemployment benefits, which began under President Donald J. Trump and are scheduled to last until September under Mr. Biden’s aid package.

Mr. Biden said on Friday that the benefits had helped Americans weather the storm, but that they would expire in 90 days. “That makes sense,” he said, noting that the license was set to expire in 90 days.

Last month, White House economists stated that there was no evidence in the numbers that the supplement was discouraging work, instead pointing to constraints such as school closures and child care issues keeping women with children from returning to work, as well as a large number of working-age Americans who had not been fully vaccinated. On Friday, administration economists doubled down on that reading.

“It is too soon to conclude that labor supply issues are impeding the long-term path of the recovery,” wrote Cecilia Rouse, chair of the White House Council of Economic Advisers, in a blog post on Friday morning.

Democratic leaders in Congress continued to press for the continuation of unemployment benefits and for lawmakers to move forward with the rest of Mr. Biden’s $4 trillion economic agenda.

“The American people need all the help they can get, especially Black and Hispanic communities, which were among the hardest hit by the pandemic,” said Virginia Representative Don Beyer, chairman of the Joint Economic Committee, in a news release. “Lawmakers must take action. This includes the continuation of enhanced unemployment insurance to assist workers looking for work and the passage of President Biden’s Jobs and Families Plans by Congress.”