WASHINGTON — With his party facing potentially gale-force headwinds in the midterm elections, President Biden on Monday tacked toward the political center with a budget that would bolster military and law enforcement spending while tackling inflation and deficit reduction in service of what he called a “bipartisan unity agenda.”

The core of his proposed budget for the fiscal year that begins a month before the midterms did not change significantly from his first budget blueprint a year ago. To universal prekindergarten and combating climate change he actually added a new tax on the wealth of billionaires.

But its framing was a marked shift from the 2021 pitch for a fundamental transformation of an ailing American society. Instead, Mr. Biden’s plan was an appeal based on the reality of the moment, to both new dangers around the globe and at home, where inflation and crime are crushing the president’s political standing.

Endangered Democrats in swing districts have been urging Mr. Biden to counter the messages from the far left and address the kitchen-table issues facing voters with incremental steps, not transformative legislation. For them, the budget promises deficit reduction to cool the economy and tangible steps to unclog supply-chain bottlenecks that contribute to rising prices.

The heft of his message this year comes not from an urgent appeal to address racial and income inequality, climate change and the struggles of the middle class, but to reassert American dominance in a dangerous and competitive world.

“We are at the beginning of a decisive decade that will determine the future of strategic competition with China, the trajectory of the climate crisis and whether the rules governing technology, trade and international economics enshrine or violate our democratic values,” the budget states, justifying large increases to project U.S. military and diplomatic strength globally.

Under the new plan, the left wing’s hopes for a peace dividend at the end of wars in Iraq and Afghanistan would be scotched in favor of a new great powers military budget that would bring the Defense Department’s allocation to $773 billion, an increase of nearly 10 percent over the level for the 2021 fiscal year. Rather than cuts, Mr. Biden pledges to bolster the nation’s nuclear weapons program, including all three legs of the nuclear “triad”: bombers, land-based intercontinental missiles and submarines.

Domestically, the big-ticket items from last year are still there: universal prekindergarten, generous subsidies for child care and commitments to clean, renewable energy. Representative Ro Khanna of California, a prominent progressive, praised the proposed 20 percent minimum tax on billionaires that would, for the first time, tax unrealized gains on assets if income taxes fell short of the minimum.

“As a representative of Silicon Valley that arguably has more billionaires than anywhere in the world,” Mr. Khanna said, “I have been saying for years, raise their taxes to help build a society with fair opportunity for everyone.”

But that is not where the president’s emphasis was. He relegated much of his Build Back Better domestic policy agenda — a nearly $2 trillion smorgasbord of proposed safety net and climate programs that drew unanimous Republican opposition and fractured his own party — to a single line item in the budget document, with no price tag and no detail, leaving it to Congress to determine if any of it could be salvaged. And he made a concerted effort to take the sting out of the issues of crime and immigration that Republicans have been using against Democrats.

Far from defunding the police and abolishing Immigration and Customs Enforcement, two popular slogans on the left, the budget robustly funds both. Customs and Border Protection would receive $15.3 billion and ICE $8.1 billion, including $309 million for border security technology — a well-funded effort to stop illegal migration. The nation’s two primary immigration law enforcement agencies would see increases of around 13 percent.

The budget even includes $19 million for border fencing and other infrastructure.

Federal law enforcement would receive $17.4 billion, a jump of nearly 11 percent, or $1.7 billion, over 2021 levels. And the president, acknowledging widespread concerns that are driving Republican attacks against Democrats, vowed to tackle the rise in violent crime.

“The answer is not to defund our police departments,” Mr. Biden said at the White House on Monday. “It is to fund our police and give them all the tools they need.”

The proposals track with some of the main attack lines Republicans are using against Democrats in the run-up to the November contests, as they portray Mr. Biden and his allies in Congress as weak on security, soft on crime and profligate with federal spending to the point of damaging the economy.

Liberal Democrats would see some of their priorities addressed, including substantial funding for climate programs and “environmental justice” initiatives, as well as changes to incarceration policy. But some progressives were left deeply disappointed. In lieu of broad student debt forgiveness, an executive order that many Democrats have been pressing for since Mr. Biden’s inauguration, the Education Department’s student lending services would receive a huge increase, 43 percent, to $2.7 billion.

Activist groups that had helped shift the Democratic Party leftward were not giving up. Immigrants’ rights groups calling themselves Defund Hate planned a news conference for Tuesday to “outline their expectations for President Biden to redirect billions in funding from immigration enforcement, militarization and policing toward humane, community-based resources that invest in the true needs of Black, brown and immigrant communities.”

The Movement for Black Lives denounced a budget that would spend $30 billion on policing and only $367 million on “police reform, the prosecution of hate crimes, enforcement of voting rights and efforts to provide equitable access to justice.”

Mr. Biden purposely shrugged such criticism off. “Isn’t it kind of fascinating that when I first got elected, I was being beat up because I supported the police too much for a period of 30 years?” he told reporters when asked if he was responding to Republican attacks. “No, that’s what I think.”

Republicans indicated they were not about to shift their lines of attack.

“Don’t let Biden’s budget fool you — Biden does not support the police,” said a statement the Republican National Committee issued on Monday. “If he did, he would call on Democrat-run cities to stop undermining law enforcement.”

In Congress, Republicans zeroed in on the substance of the budget, not the message, emphasizing that it would increase funding for climate programs and other liberal priorities that did not get much ink beyond the spending tables.

“President Biden would rather grind his ideological ax and escalate his holy war on made-in-America fossil fuels,” said Senator Mitch McConnell of Kentucky, the Republican leader.

Nor do Republicans believe the president can shift the narrative now. The realities of rising prices and violent crime are not likely to change by November, and even if they do, voter perceptions tend to lag.

“Kitchen-table issues like rising prices, the economy and public safety will take the front seat in November,” predicted Calvin Moore, a spokesman for the Congressional Leadership Fund, the main G.O.P. super PAC trying to deliver a Republican majority in November.

Democratic leaders latched on to the shifting message. The Democratic National Committee on Monday blasted out the headlines it liked, which were decidedly not grandiose. One from Detroit blared, “Biden’s Nearly $6T Budget Aims to Bolster EVs, Great Lakes and PFAS Cleanup,” referring to money for electric vehicles and getting rid of a dangerous manufactured chemical that has tainted water supplies in industrial regions. Another, from Miami, celebrated that “Biden Seeks More Money for Everglades Restoration in 2023 Budget.” In Harrisburg, Pa., the story was, “Biden Lays Out a ‘Fund the Police’ Budget Plan.”