Elon Musk is calling on Americans to reject the “disgusting abomination” of a spending bill before Congress. To soothe the deficit hawk’s feathers, expect President Trump to repeat a classic GOP prescription: America can grow its way out of deficits with business-friendly, supply-side policies.

Mr. Musk on Wednesday urged followers on X to send their representatives a message to “KILL THE BILL,” writing that “bankrupting America is NOT ok!” On Tuesday, he wrote, “I just can’t stand it anymore,” calling the legislation “outrageous” and “pork-filled” and casting “shame on those who voted for it.”

Yet “politics,” the Iron Chancellor of Germany, Otto von Bismarck, said, “is the art of the possible, the attainable — the art of the next best.” With a narrow Republican majority unable to pass DOGE-level cuts, holding the line on spending and growing out of the deficit looks to be the next-best path available. 

Mr. Musk — the GOP’s largest donor in 2024 — wants it all now. “The Debt Slavery Bill,” he said, contains “the largest increase in the debt ceiling in US history.” In next year’s midterms, he said, “fire all politicians who betrayed the American people.”

A White House proposal would nibble just $9.4 billion from the bill, less than half a penny on the dollar against Mr. Musk’s $2 trillion target for DOGE. However, accumulating debt — and government spending — helped Mr. Musk build his empire. 

In 2010, the Department of Energy lent Tesla $465 million. In October 1963, defending a dam project condemned as pork, President Kennedy argued that investments like the one given to Mr. Musk would boost the Treasury. “A rising tide,” he said, “lifts all the boats.” 

Republicans are arguing that pro-growth policies will more than pay for spending. They’re also casting doubt on the Congressional Budget Office, which scored a $3.7 trillion loss from the bill’s tax cuts and a deficit increase of $2.5 trillion. 

The CBO analysis is static, and those like Mr. Musk who make up the economy are dynamic, responding to incentives. The CBO, Republicans note, also scored based on a rather anemic economic growth rate of 1.8 percent. 

Republicans used 2.6 percent and, on Monday, learned that even this might be lowballing. The Atlanta Federal Reserve forecast 4.6 percent growth in 2025’s second quarter.

The CBO’s calculation is “extremely low,” Mr. Trump wrote Friday on Truth Social. “I predict we will do 3, 4, or even 5 times” the 1.8 percent figure. “With just our minimum expected 3% growth, we will more than offset our tax cuts.” He noted his growth rate had “doubled” the CBO’s forecast in 2017.

A former director of the Mr. Trump’s National Economic Council, Lawrence Kudlow, recounted that history on Wednesday in his column in the Sun. “Seven years ago,” he said, “the CBO underscored Mr. Trump’s tax-cut related revenues by $2.3 trillion.” 

The CBO also predicted a loss from President Reagan’s 1981 tax reform. Instead, the economy almost doubled in eight years. That the Democratic Congress kept spending faster than the cash came in helped Republicans win both chambers in 1994. 

That Republican Congress delivered the first budget surplus since 1969. Like Reagan, Kennedy sparked a boom by stimulating growth. In 1963 at the Economic Club of New York, he called it “a paradoxical truth” that taxes were “too high” and revenues “too low.”

Kennedy said that “an economy hampered by restrictive tax rates will never produce enough revenues to balance our budget.” He argued that “the soundest way to raise the revenues in the long run is to cut the rates now.” 

Secretary Bessent echoed this on X two weeks ago. “We are going to grow the GDP faster,” he said, “than the debt grows.” He, like Mr. Trump, shares the faith of Kennedy and Reagan that reducing the tax burden will unleash economic growth and balance the budget. 

Mr. Musk is new to Washington’s art of the possible. To coax him back on board, Republicans will have to convince him that fiscal solvency can be achieved by raising the tide to lift all boats — the next-best path to fiscal solvency after spending cuts, and far better than sinking their bill with all hands on deck.