“This is a good budget if you want to spend your time fighting small fires,” said former Senator Judd Gregg of New Hampshire, who as the Republican chairman of the Senate Budget Committee spent years trying to rally lawmakers to do the hard work to balance the budget. “It’s a statement of policy, which is legitimate, that the government is too big,” Mr. Gregg said. “As a practical matter, it does not affect the big issues that drive that.”
Congress could have eliminated every penny of domestic spending at its annual discretion this year, and it would not have balanced the federal budget, according to Congressional Budget Office projections, much less rid the nation of its nearly $20 trillion in government debt — which Mr. Trump told voters he could do easily in eight years.
It is precisely what conservatives have wanted to control.
“The fact is that until the president and Congress are willing to address the real drivers of our debt, Medicare and Social Security, we will be complicit in shackling future generations with the financial burden of our own lack of discipline,” said Senator Bob Corker, Republican of Tennessee. “That is not a legacy I want to leave.”
Mick Mulvaney, Mr. Trump’s budget director, who as a member of the House was one of the biggest deficit hawks, was confronted with the budget’s failure to deal with the debt in a news conference with reporters on Thursday.
“It’s a fair question,” he said. “I would just suggest to you it’s not the right time for the question. The budget blueprint, again, does not deal with the debt. It even doesn’t even deal with the deficit. It is simply the first part of the appropriations process.”
The budget document represents a broad-brush aspiration for Mr. Trump, leaving it to the House and Senate appropriations committees to do all the painful work, like finding a way to pay for a wall along the Mexican border that the White House wants.
But trying to pass appropriations bills with large cuts to popular domestic programs seems almost impossible in both chambers, especially the Senate, leading Congress on another path to short-term spending measures that Republicans have long wanted to escape.
The Congressional Budget Office foresees a federal deficit for the 2018 fiscal year of $487 billion, rising steadily from there until it reaches $1 trillion in 2023. But that is driven all by an aging population, rising health care costs and rising interest payments from the escalating debt.
Projected declines in discretionary spending under Mr. Trump’s plan would be more than swallowed by rising payments to Social Security and Medicare because the population aged 65 and older is expected to grow by 39 percent through 2027. In that time, spending on people 65 and older who receive Social Security, Medicare, Medicaid and military and federal civilian retirement income will rise from 37 percent of federal spending in 2017 to 45 percent in 10 years.
And many of his proposed cuts are at odds with congressional priorities.
His budget cuts spending for the National Institutes of Health, which lawmakers gave a big funding increase last year to help attack cancer and other diseases; community block grants, which help feed hungry children (a Democratic priority); and local law enforcement (popular with Republicans); as well as pet programs like funding to care for the Great Lakes, which Midwestern lawmakers have fought hard to maintain.
“The president proposes and Congress disposes,” said Representative Charlie Dent, a Republican appropriator from Pennsylvania. “We can’t finance a defense buildup entirely on the back of domestic, nondefense spending. It’s not realistic and unfair.”
Mr. Trump’s budget also shows little regard for the political sensitivities of his party. His proposal to restart licensing for a nuclear waste repository in Yucca Mountain, in Nevada, creates a headache for Senator Dean Heller, a Republican who is up for re-election in that state next year. His response was swift and blunt. “As has been stated in the past, Yucca is dead, and this reckless proposal will not revive it,” he said in a statement.
It even takes an ax to programs that are important to the Senate majority leader, Mitch McConnell, Republican of Kentucky, by proposing cuts in funding for the Appalachian Regional Commission and some air service that would probably eliminate two airports in his state.
Mr. McConnell on Thursday went in search of a silver lining.
“I’m pleased to see an increased focus on our national security and veterans budgets,” he said in a statement. “These are positive steps in the right direction. I look forward to reviewing this and the full budget when it is released later this spring.”
Mr. Trump is hardly alone in putting forth a budget dismissed by his own party. Mr. Obama pushed the idea of changing the way the inflation rate was calculated to slow the growth of big programs like Social Security, a proposal many Democrats opposed. President George W. Bush pressed to partially privatize Social Security, and many Republicans disliked that idea.
But it is striking to read Mr. Trump’s budget and see clearly mixed messages from the opening pages delivered by Mr. Mulvaney, who praised the budget as a debt crusher, and from Mr. Trump, who emphasized his increases in military spending.
Those contradictions are among the many reasons that even members of Mr. Trump’s party see his budget more as a mere suggestion than an edict.
“Historically, presidential budgets do not fare well with Congress,” said Senator Lindsey Graham, Republican of South Carolina.