During the first two years of his presidency, President Biden spent trillions of taxpayer dollars on everything from Covid relief and student loan deferrals to Ukraine and climate-related subsidies. Now, the administration is declaring itself a budget hawk and insisting that the perennial gap between what the government spends and what it takes in from taxes must be reduced.

The positioning portends a struggle in Congress in the coming weeks as Mr. Biden prepares to deliver a proposed budget for 2023. His maneuvering will force Republicans to reconcile their budget-cutting rhetoric with the political reality of actually cutting government spending.

For months, Democrats have been demanding that Republicans, who have been brandishing the threat of a debt default, show them a budget plan. Now, the president is about to show them his, one that is expected to include some modest spending cuts along with tax increases on corporations and upper-income Americans.

“The plan I’m going to show you is going to cut the deficit by another $2 trillion,” Mr. Biden said at the State of the Union.

Although the administration’s 2023 budget is also focused on increasing revenue, in an effort to appease Senator Manchin, the new focus on reducing the deficit marks a change of tune for the administration. Now, the talking point is that Mr. Biden and his surrogates have reduced the deficit during his time in office.

“This president takes a backseat to nobody on deficit reduction,”  the director of the Office of Management and Budget, Shalanda Young, told MSNBC. “The budget will continue the trajectory on reduction.”

The national deficit has fallen by about $1.7 trillion during Mr. Biden’s time in office. In fiscal year 2023, the government is expected to run a $1.4 trillion deficit, which will be about the same as the previous year but a significant increase over deficit spending before the pandemic. In fiscal year 2019, the last full year before the pandemic, the federal government ran a $984 billion deficit.

Republicans in Congress have argued that Mr. Biden does not deserve credit for those reductions because much of it is attributable to the expiration of policies and pandemic-era provisions from President Trump’s tenure. Others have argued that the federal deficit would have fallen even more absent Mr. Biden’s spendthrift policies.

One of those critics, Representative Ralph Norman, has become a point man for House Republicans in internal budget negotiations, a role he won by agreeing to support Speaker McCarthy during his campaign to gain the speaker’s seat.

According to Mr. Norman, every “major piece of financial legislation — including this upcoming debt ceiling package — MUST come with some incremental cuts to non-military, discretionary spending.”

Mr. Norman was one of a minority of Republicans who opposed debt limit increases or suspensions the three times the issue was brought to a vote under Mr. Trump, in 2017, 2018, and 2019.

This pledge to cut spending without naming any specific programs to be cut has become typical of Republicans speaking on the topic in 2023. Mr. Norman, like many other Republicans, has said he wants to cut the budget without touching military or mandatory spending, the vast majority of which is on programs like Social Security or Medicare. 

The problem, though, is that these two categories of spending — military discretionary spending and mandatory spending — together make up the vast majority of federal spending. Cutting the budget without touching either of these categories would mean that Republicans would need to cut all other government programs to the bone.

According to a Congressional Budget Office estimate, if only Social Security and Medicare are exempt from cuts, all other spending would need to be cut by 44 percent to produce a balanced budget.

The difficult math, along with earlier promises from some GOP senators to cut entitlement programs, has provided a lane for Democrats to question Republicans’ credibility in their promises not to touch entitlement programs or military spending, which amounted to about $800 billion last year.

“If you want to protect Social Security and Medicare, that’s fine. How about our veterans? How about Medicaid programs that go to the states?” the Democratic House Caucus chairman, Peter Aguilar, told reporters. 

“And we would welcome their pledge to protect Social Security and Medicare,” Mr. Aguilar added. “I just don’t know that we can believe it.”

With Mr. Biden expected to deliver a full proposed budget next week, Republicans will soon be forced to put up their own concrete plan. So far, the closest House Republicans have come to such a plan is to cut what a former director of the Office of Management and Budget, Russell Vought, has described to Reuters as “significantly woke and unaccountable” bureaucracy. 

“We’re in a divided government,” Mr. Vought said. “So what’s the easiest place to cut spending? It’s the bureaucracy, and that’s where we want to focus the fight.”

Mr. Vought, who has been brought in to help House Republicans build a plan, has said they’re planning to propose $150 billion in non-defense discretionary spending cuts, a category that only makes up around $900 billion of the $5.8 trillion fiscal year 2023 federal budget.